HTML 5.1

None.

As the root element of a document.

Wherever a subdocument fragment is allowed in a compound document.

A head element followed by a body element.

An html element's start tag can be omitted if the first thing inside the html element is not a comment.

An html element's end tag can be omitted if the html element is not immediately followed by a comment.

manifest — Application cache manifest

Allowed ARIA role attribute values:

None

interface HTMLHtmlElement : HTMLElement {
  // also has obsolete members
};

The html element represents the root of an HTML document.

Authors are encouraged to specify a lang attribute on the root html element, giving the document's language. This aids speech synthesis tools to determine what pronunciations to use, translation tools to determine what rules to use, and so forth.

The manifest attribute gives the address of the document's application cache manifest, if there is one. If the attribute is present, the attribute's value must be a valid non-empty URL potentially surrounded by spaces.

The manifest attribute only has an effect during the early stages of document load. Changing the attribute dynamically thus has no effect (and thus, no DOM API is provided for this attribute).

For the purposes of application cache selection, later base elements cannot affect the resolving of relative URLs in manifest attributes, as the attributes are processed before those elements are seen.

The window.applicationCache IDL attribute provides scripted access to the offline application cache mechanism.

The html element in the following example declares that the document's language is English.

<!DOCTYPE html>
<html lang="en">
<head>
<title>Swapping Songs</title>
</head>
<body>
<h1>Swapping Songs</h1>
<p>Tonight I swapped some of the songs I wrote with some friends, who
gave me some of the songs they wrote. I love sharing my music.</p>
</body>
</html>

4.2 Document metadata

4.2.1 The `head` element

None.

As the first element in an html element.

If the document is an iframe srcdoc document or if title information is available from a higher-level protocol: Zero or more elements of metadata content, of which no more than one is a title element and no more than one is a base element.

Otherwise: One or more elements of metadata content, of which exactly one is a title element and no more than one is a base element.

A head element's start tag can be omitted if the element is empty, or if the first thing inside the head element is an element.

A head element's end tag can be omitted if the head element is not immediately followed by a space character or a comment.

Allowed ARIA role attribute values:

None

interface HTMLHeadElement : HTMLElement {};

The head element represents a collection of metadata for the Document.

The collection of metadata in a head element can be large or small. Here is an example of a very short one:

<!doctype html>
<html>
 <head>
  <title>A document with a short head</title>
 </head>
 <body>
 ...

Here is an example of a longer one:

<!DOCTYPE HTML>
<HTML>
 <HEAD>
  <META CHARSET="UTF-8">
  <BASE HREF="http://www.example.com/">
  <TITLE>An application with a long head</TITLE>
  <LINK REL="STYLESHEET" HREF="default.css">
  <LINK REL="STYLESHEET ALTERNATE" HREF="big.css" TITLE="Big Text">
  <SCRIPT SRC="support.js"></SCRIPT>
  <META NAME="APPLICATION-NAME" CONTENT="Long headed application">
 </HEAD>
 <BODY>
 ...

The title element is a required child in most situations, but when a higher-level protocol provides title information, e.g. in the Subject line of an e-mail when HTML is used as an e-mail authoring format, the title element can be omitted.

4.2.2 The `title` element

In a head element containing no other title elements.

Text that is not inter-element whitespace.

Neither tag is omissible.

Allowed ARIA role attribute values:

None

interface HTMLTitleElement : HTMLElement {
  attribute DOMString text;
};

The title element represents the document's title or name. Authors should use titles that identify their documents even when they are used out of context, for example in a user's history or bookmarks, or in search results. The document's title is often different from its first heading, since the first heading does not have to stand alone when taken out of context.

There must be no more than one title element per document.

If it's reasonable for the Document to have no title, then the title element is probably not required. See the head element's content model for a description of when the element is required.

title . text [ = value ]

Returns the contents of the element, ignoring child nodes that aren't Text nodes.

Can be set, to replace the element's children with the given value.

The IDL attribute text must return a concatenation of the contents of all the Text nodes that are children of the title element (ignoring any other nodes such as comments or elements), in tree order. On setting, it must act the same way as the textContent IDL attribute.

Here are some examples of appropriate titles, contrasted with the top-level headings that might be used on those same pages.

  <title>Introduction to The Mating Rituals of Bees</title>
    ...
  <h1>Introduction</h1>
  <p>This companion guide to the highly successful
  <cite>Introduction to Medieval Bee-Keeping</cite> book is...

The next page might be a part of the same site. Note how the title describes the subject matter unambiguously, while the first heading assumes the reader knows what the context is and therefore won't wonder if the dances are Salsa or Waltz:

  <title>Dances used during bee mating rituals</title>
    ...
  <h1>The Dances</h1>

The string to use as the document's title is given by the document.title IDL attribute.

User agents should use the document's title when referring to the document in their user interface. When the contents of a title element are used in this way, the directionality of that title element should be used to set the directionality of the document's title in the user interface.

4.2.3 The `base` element

In a head element containing no other base elements.

No end tag.

href — Document base URL

target — Default browsing context for hyperlink navigation and form submission

Allowed ARIA role attribute values:

None

Global aria-* attributes.

interface HTMLBaseElement : HTMLElement {
  attribute DOMString href;
  attribute DOMString target;
};

The base element allows authors to specify the document base URL for the purposes of resolving relative URLs, and the name of the default browsing context for the purposes of following hyperlinks. The element does not represent any content beyond this information.

There must be no more than one base element per document.

A base element must have either an href attribute, a target attribute, or both.

The href content attribute, if specified, must contain a valid URL potentially surrounded by spaces.

A base element, if it has an href attribute, must come before any other elements in the tree that have attributes defined as taking URLs, except the html element (its manifest attribute isn't affected by base elements).

If there are multiple base elements with href attributes, all but the first are ignored.

The target attribute, if specified, must contain a valid browsing context name or keyword, which specifies which browsing context is to be used as the default when hyperlinks and forms in the Document cause navigation.

A base element, if it has a target attribute, must come before any elements in the tree that represent hyperlinks.

If there are multiple base elements with target attributes, all but the first are ignored.

A base element that is the first base element with an href content attribute in a particular Document has a frozen base URL. The frozen base URL must be immediately set whenever any of the following situations occur:

The base element becomes the first base element in tree order with an href content attribute in its Document.
The base element is the first base element in tree order with an href content attribute in its Document, and its href content attribute is changed.

To set the frozen base URL, resolve the value of the element's href content attribute relative to the Document's fallback base URL; if this is successful, set the frozen base URL to the resulting absolute URL, otherwise, set the frozen base URL to the fallback base URL.

The href IDL attribute, on getting, must return the result of running the following algorithm:

If the base element has no href content attribute, then return the document base URL and abort these steps.
Let fallback base url be the Document's fallback base URL.
Let url be the value of the href attribute of the base element.
Resolve url relative to fallback base url (thus, the base's href attribute isn't affected by other base elements).
If the previous step was successful, return the resulting absolute URL and abort these steps.
Otherwise, return the empty string.

The href IDL attribute, on setting, must set the href content attribute to the given new value.

The target IDL attribute must reflect the content attribute of the same name.

In this example, a base element is used to set the document base URL:

<!DOCTYPE html>
<html>
    <head>
        <title>This is an example for the &lt;base&gt; element</title>
        <base href="http://www.example.com/news/index.html">
    </head>
    <body>
        <p>Visit the <a href="archives.html">archives</a>.</p>
    </body>
</html>

The link in the above example would be a link to "http://www.example.com/news/archives.html".

4.2.4 The `link` element

If the itemprop attribute is present: flow content.

If the itemprop attribute is present: phrasing content.

Where metadata content is expected.

In a noscript element that is a child of a head element.

If the itemprop attribute is present: where phrasing content is expected.

No end tag.

href — Address of the hyperlink

crossorigin — How the element handles crossorigin requests

rel — Relationship between the document containing the hyperlink and the destination resource

media — Applicable media

hreflang — Language of the linked resource

type — Hint for the type of the referenced resource

sizes — Sizes of the icons (for rel="icon")

Also, the title attribute has special semantics on this element: Title of the link; alternative style sheet set name.

Allowed ARIA role attribute values:

link (default - do not set).

Any aria-* attributes applicable to the allowed roles.

For role value

interface HTMLLinkElement : HTMLElement {
  attribute DOMString href;
  attribute DOMString? crossOrigin;
  attribute DOMString rel;
  readonly attribute DOMTokenList relList;
  attribute DOMString media;
  attribute DOMString hreflang;
  attribute DOMString type;
  [PutForwards=value] readonly attribute DOMSettableTokenList sizes;

  // also has obsolete members
};
HTMLLinkElement implements LinkStyle;

The link element allows authors to link their document to other resources.

The destination of the link(s) is given by the href attribute, which must be present and must contain a valid non-empty URL potentially surrounded by spaces. If the href attribute is absent, then the element does not define a link.

A link element must have either a rel attribute or an itemprop attribute, but not both.

If the rel attribute is used, the element is restricted to the head element. When used with the itemprop attribute, the element can be used both in the head element and in the body of the page, subject to the constraints of the microdata model.

The types of link indicated (the relationships) are given by the value of the rel attribute, which, if present, must have a value that is a set of space-separated tokens. The allowed keywords and their meanings are defined in a later section. If the rel attribute is absent, has no keywords, or if none of the keywords used are allowed according to the definitions in this specification, then the element does not create any links.

Two categories of links can be created using the link element: Links to external resources and hyperlinks. The link types section defines whether a particular link type is an external resource or a hyperlink. One link element can create multiple links (of which some might be external resource links and some might be hyperlinks); exactly which and how many links are created depends on the keywords given in the rel attribute. User agents must process the links on a per-link basis, not a per-element basis.

Each link created for a link element is handled separately. For instance, if there are two link elements with rel="stylesheet", they each count as a separate external resource, and each is affected by its own attributes independently. Similarly, if a single link element has a rel attribute with the value next stylesheet, it creates both a hyperlink (for the next keyword) and an external resource link (for the stylesheet keyword), and they are affected by other attributes (such as media or title) differently.

For example, the following link element creates two hyperlinks (to the same page):

<link rel="author license" href="/about">

The two links created by this element are one whose semantic is that the target page has information about the current page's author, and one whose semantic is that the target page has information regarding the license under which the current page is provided.

The crossorigin attribute is a CORS settings attribute. It is intended for use with external resource links.

The exact behaviour for links to external resources depends on the exact relationship, as defined for the relevant link type. Some of the attributes control whether or not the external resource is to be applied (as defined below).

For external resources that are represented in the DOM (for example, style sheets), the DOM representation must be made available (modulo cross-origin restrictions) even if the resource is not applied. To obtain the resource, the user agent must run the following steps:

If the href attribute's value is the empty string, then abort these steps.
Resolve the URL given by the href attribute, relative to the element.
If the previous step fails, then abort these steps.
Let corsAttributeState be the current state of the element's crossorigin content attribute.
Let request be the result of creating a potential-CORS request given the absolute URL and corsAttributeState.
Set request's client to the link element's node document's Window object's environment settings object.
Fetch request.

User agents may opt to only try to obtain such resources when they are needed, instead of pro-actively fetching all the external resources that are not applied.

The semantics of the protocol used (e.g. HTTP) must be followed when fetching external resources. (For example, redirects will be followed and 404 responses will cause the external resource to not be applied.)

Once the attempts to obtain the resource and its critical subresources are complete, the user agent must, if the loads were successful, queue a task to fire a simple event named load at the link element, or, if the resource or one of its critical subresources failed to completely load for any reason (e.g. DNS error, HTTP 404 response, a connection being prematurely closed, unsupported Content-Type), queue a task to fire a simple event named error at the link element. Non-network errors in processing the resource or its subresources (e.g. CSS parse errors, PNG decoding errors) are not failures for the purposes of this paragraph.

The task source for these tasks is the DOM manipulation task source.

The element must delay the load event of the element's node document until all the attempts to obtain the resource and its critical subresources are complete. (Resources that the user agent has not yet attempted to obtain, e.g. because it is waiting for the resource to be needed, do not delay the load event.)

Interactive user agents may provide users with a means to follow the hyperlinks created using the link element, somewhere within their user interface. The exact interface is not defined by this specification, but it could include the following information (obtained from the element's attributes, again as defined below), in some form or another (possibly simplified), for each hyperlink created with each link element in the document:

The relationship between this document and the resource (given by the rel attribute)
The title of the resource (given by the title attribute).
The address of the resource (given by the href attribute).
The language of the resource (given by the hreflang attribute).
The optimum media for the resource (given by the media attribute).

User agents could also include other information, such as the type of the resource (as given by the type attribute).

Hyperlinks created with the link element and its rel attribute apply to the whole page. This contrasts with the rel attribute of a and area elements, which indicates the type of a link whose context is given by the link's location within the document.

The media attribute says which media the resource applies to. The value must be a valid media query list.

If the link is a hyperlink then the media attribute is purely advisory, and describes for which media the document in question was designed.

However, if the link is an external resource link, then the media attribute is prescriptive. The user agent must apply the external resource when the media attribute's value matches the environment and the other relevant conditions apply, and must not apply it otherwise.

The external resource might have further restrictions defined within that limit its applicability. For example, a CSS style sheet might have some @media blocks. This specification does not override such further restrictions or requirements.

The default, if the media attribute is omitted, is "all", meaning that by default links apply to all media.

The hreflang attribute on the link element has the same semantics as the hreflang attribute on a and area elements.

The type attribute gives the MIME type of the linked resource. It is purely advisory. The value must be a valid MIME type.

For external resource links, the type attribute is used as a hint to user agents so that they can avoid fetching resources they do not support. If the attribute is present, then the user agent must assume that the resource is of the given type (even if that is not a valid MIME type, e.g. the empty string). If the attribute is omitted, but the external resource link type has a default type defined, then the user agent must assume that the resource is of that type. If the UA does not support the given MIME type for the given link relationship, then the UA should not obtain the resource; if the UA does support the given MIME type for the given link relationship, then the UA should obtain the resource at the appropriate time as specified for the external resource link's particular type. If the attribute is omitted, and the external resource link type does not have a default type defined, but the user agent would obtain the resource if the type was known and supported, then the user agent should obtain the resource under the assumption that it will be supported.

User agents must not consider the type attribute authoritative — upon fetching the resource, user agents must not use the type attribute to determine its actual type. Only the actual type (as defined in the next paragraph) is used to determine whether to apply the resource, not the aforementioned assumed type.

If the external resource link type defines rules for processing the resource's Content-Type metadata, then those rules apply. Otherwise, if the resource is expected to be an image, user agents may apply the image sniffing rules, with the official type being the type determined from the resource's Content-Type metadata, and use the resulting sniffed type of the resource as if it was the actual type. Otherwise, if neither of these conditions apply or if the user agent opts not to apply the image sniffing rules, then the user agent must use the resource's Content-Type metadata to determine the type of the resource. If there is no type metadata, but the external resource link type has a default type defined, then the user agent must assume that the resource is of that type.

The stylesheet link type defines rules for processing the resource's Content-Type metadata.

Once the user agent has established the type of the resource, the user agent must apply the resource if it is of a supported type and the other relevant conditions apply, and must ignore the resource otherwise.

If a document contains style sheet links labeled as follows:

<link rel="stylesheet" href="A" type="text/plain">
<link rel="stylesheet" href="B" type="text/css">
<link rel="stylesheet" href="C">

...then a compliant UA that supported only CSS style sheets would fetch the B and C files, and skip the A file (since text/plain is not the MIME type for CSS style sheets).

For files B and C, it would then check the actual types returned by the server. For those that are sent as text/css, it would apply the styles, but for those labeled as text/plain, or any other type, it would not.

If one of the two files was returned without a Content-Type metadata, or with a syntactically incorrect type like Content-Type: "null", then the default type for stylesheet links would kick in. Since that default type is text/css, the style sheet would nonetheless be applied.

The title attribute gives the title of the link. With one exception, it is purely advisory. The value is text. The exception is for style sheet links, where the title attribute defines alternative style sheet sets.

The title attribute on link elements differs from the global title attribute of most other elements in that a link without a title does not inherit the title of the parent element: it merely has no title.

The sizes attribute is used with the icon link type. The attribute must not be specified on link elements that do not have a rel attribute that specifies the icon keyword.

The activation behaviour of link elements that create hyperlinks is to run the following steps:

If the link element's node document is not fully active, then abort these steps.
Follow the hyperlink created by the link element.

HTTP `Link` headers, if supported, must be assumed to come before any links in the document, in the order that they were given in the HTTP message. These headers are to be processed according to the rules given in the relevant specifications. [HTTP] [WEBLINK]

Registration of relation types in HTTP `Link` headers is distinct from HTML link types, and thus their semantics can be different from same-named HTML types.

The IDL attributes href, rel, media, hreflang, type, and sizes each must reflect the respective content attributes of the same name.

The crossOrigin IDL attribute must reflect the crossorigin content attribute.

The IDL attribute relList must reflect the rel content attribute.

The LinkStyle interface is also implemented by this element. [CSSOM]

Here, a set of link elements provide some style sheets:

<!-- a persistent style sheet -->
<link rel="stylesheet" href="default.css">

<!-- the preferred alternate style sheet -->
<link rel="stylesheet" href="green.css" title="Green styles">

<!-- some alternate style sheets -->
<link rel="alternate stylesheet" href="contrast.css" title="High contrast">
<link rel="alternate stylesheet" href="big.css" title="Big fonts">
<link rel="alternate stylesheet" href="wide.css" title="Wide screen">

The following example shows how you can specify versions of the page that use alternative formats, are aimed at other languages, and that are intended for other media:

<link rel=alternate href="/en/html" hreflang=en type=text/html title="English HTML">
<link rel=alternate href="/fr/html" hreflang=fr type=text/html title="French HTML">
<link rel=alternate href="/en/html/print" hreflang=en type=text/html media=print title="English HTML (for printing)">
<link rel=alternate href="/fr/html/print" hreflang=fr type=text/html media=print title="French HTML (for printing)">
<link rel=alternate href="/en/pdf" hreflang=en type=application/pdf title="English PDF">
<link rel=alternate href="/fr/pdf" hreflang=fr type=application/pdf title="French PDF">

4.2.5 The `meta` element

If the itemprop attribute is present: flow content.

If the itemprop attribute is present: phrasing content.

If the charset attribute is present, or if the element's http-equiv attribute is in the Encoding declaration state: in a head element.

If the http-equiv attribute is present but not in the Encoding declaration state: in a head element.

If the http-equiv attribute is present but not in the Encoding declaration state: in a noscript element that is a child of a head element.

If the name attribute is present: where metadata content is expected.

If the itemprop attribute is present: where metadata content is expected.

If the itemprop attribute is present: where phrasing content is expected.

No end tag.

name — Metadata name

http-equiv — Pragma directive

content — Value of the element

charset — Character encoding declaration

Allowed ARIA role attribute values:

None

interface HTMLMetaElement : HTMLElement {
  attribute DOMString name;
  attribute DOMString httpEquiv;
  attribute DOMString content;

  // also has obsolete members
};

The meta element represents various kinds of metadata that cannot be expressed using the title, base, link, style, and script elements.

The meta element can represent document-level metadata with the name attribute, pragma directives with the http-equiv attribute, and the file's character encoding declaration when an HTML document is serialised to string form (e.g. for transmission over the network or for disk storage) with the charset attribute.

Exactly one of the name, http-equiv, charset, and itemprop attributes must be specified.

If either name, http-equiv, or itemprop is specified, then the content attribute must also be specified. Otherwise, it must be omitted.

The charset attribute specifies the character encoding used by the document. This is a character encoding declaration. If the attribute is present in an XML document, its value must be an ASCII case-insensitive match for the string "UTF-8" (and the document is therefore forced to use UTF-8 as its encoding).

The charset attribute on the meta element has no effect in XML documents, and is only allowed in order to facilitate migration to and from XHTML.

There must not be more than one meta element with a charset attribute per document.

The content attribute gives the value of the document metadata or pragma directive when the element is used for those purposes. The allowed values depend on the exact context, as described in subsequent sections of this specification.

If a meta element has a name attribute, it sets document metadata. Document metadata is expressed in terms of name-value pairs, the name attribute on the meta element giving the name, and the content attribute on the same element giving the value. The name specifies what aspect of metadata is being set; valid names and the meaning of their values are described in the following sections. If a meta element has no content attribute, then the value part of the metadata name-value pair is the empty string.

The name and content IDL attributes must reflect the respective content attributes of the same name. The IDL attribute httpEquiv must reflect the content attribute http-equiv.

4.2.5.1 Standard metadata names

This specification defines a few names for the name attribute of the meta element.

Names are case-insensitive, and must be compared in an ASCII case-insensitive manner.

application-name

The value must be a short free-form string giving the name of the Web application that the page represents. If the page is not a Web application, the application-name metadata name must not be used. Translations of the Web application's name may be given, using the lang attribute to specify the language of each name.

There must not be more than one meta element with a given language and with its name attribute set to the value application-name per document.

User agents may use the application name in UI in preference to the page's title, since the title might include status messages and the like relevant to the status of the page at a particular moment in time instead of just being the name of the application.

To find the application name to use given an ordered list of languages (e.g. British English, American English, and English), user agents must run the following steps:

Let languages be the list of languages.
Let default language be the language of the Document's root element, if any, and if that language is not unknown.
If there is a default language, and if it is not the same language as any of the languages in languages, append it to languages.
Let winning language be the first language in languages for which there is a meta element in the Document that has its name attribute set to the value application-name and whose language is the language in question.

If none of the languages have such a meta element, then abort these steps; there's no given application name.
Return the value of the content attribute of the first meta element in the Document in tree order that has its name attribute set to the value application-name and whose language is winning language.

This algorithm would be used by a browser when it needs a name for the page, for instance, to label a bookmark. The languages it would provide to the algorithm would be the user's preferred languages.

author

The value must be a free-form string giving the name of one of the page's authors.

description

The value must be a free-form string that describes the page. The value must be appropriate for use in a directory of pages, e.g. in a search engine. There must not be more than one meta element with its name attribute set to the value description per document.

generator

The value must be a free-form string that identifies one of the software packages used to generate the document. This value must not be used on pages whose markup is not generated by software, e.g. pages whose markup was written by a user in a text editor.

Here is what a tool called "Frontweaver" could include in its output, in the page's head element, to identify itself as the tool used to generate the page:

<meta name=generator content="Frontweaver 8.2">

keywords

The value must be a set of comma-separated tokens, each of which is a keyword relevant to the page.

This page about typefaces on British motorways uses a meta element to specify some keywords that users might use to look for the page:

<!DOCTYPE HTML>
<html>
 <head>
  <title>Typefaces on UK motorways</title>
  <meta name="keywords" content="british,type face,font,fonts,highway,highways">
 </head>
 <body>
  ...

Many search engines do not consider such keywords, because this feature has historically been used unreliably and even misleadingly as a way to spam search engine results in a way that is not helpful for users.

To obtain the list of keywords that the author has specified as applicable to the page, the user agent must run the following steps:

Let keywords be an empty list.
For each meta element with a name attribute and a content attribute and whose name attribute's value is keywords, run the following substeps:
1. Split the value of the element's content attribute on commas.
2. Add the resulting tokens, if any, to keywords.
Remove any duplicates from keywords.
Return keywords. This is the list of keywords that the author has specified as applicable to the page.

User agents should not use this information when there is insufficient confidence in the reliability of the value.

For instance, it would be reasonable for a content management system to use the keyword information of pages within the system to populate the index of a site-specific search engine, but a large-scale content aggregator that used this information would likely find that certain users would try to game its ranking mechanism through the use of inappropriate keywords.

4.2.5.2 Other metadata names

Extensions to the predefined set of metadata names may be registered in the WHATWG Wiki MetaExtensions page. [WHATWGWIKI]

Anyone is free to edit the WHATWG Wiki MetaExtensions page at any time to add a type. These new names must be specified with the following information:

Keyword

The actual name being defined. The name should not be confusingly similar to any other defined name (e.g. differing only in case).

Brief description

A short non-normative description of what the metadata name's meaning is, including the format the value is required to be in.

Specification

A link to a more detailed description of the metadata name's semantics and requirements. It could be another page on the Wiki, or a link to an external page.

Synonyms

A list of other names that have exactly the same processing requirements. Authors should not use the names defined to be synonyms, they are only intended to allow user agents to support legacy content. Anyone may remove synonyms that are not used in practice; only names that need to be processed as synonyms for compatibility with legacy content are to be registered in this way.

Status

One of the following:

Proposed: The name has not received wide peer review and approval. Someone has proposed it and is, or soon will be, using it.
Ratified: The name has received wide peer review and approval. It has a specification that unambiguously defines how to handle pages that use the name, including when they use it in incorrect ways.
Discontinued: The metadata name has received wide peer review and it has been found wanting. Existing pages are using this metadata name, but new pages should avoid it. The "brief description" and "specification" entries will give details of what authors should use instead, if anything.

If a metadata name is found to be redundant with existing values, it should be removed and listed as a synonym for the existing value.

If a metadata name is registered in the "proposed" state for a period of a month or more without being used or specified, then it may be removed from the registry.

If a metadata name is added with the "proposed" status and found to be redundant with existing values, it should be removed and listed as a synonym for the existing value. If a metadata name is added with the "proposed" status and found to be harmful, then it should be changed to "discontinued" status.

Anyone can change the status at any time, but should only do so in accordance with the definitions above.

Conformance checkers may use the information given on the WHATWG Wiki MetaExtensions page to establish if a value is allowed or not: values defined in this specification or marked as "proposed" or "ratified" must be accepted, whereas values marked as "discontinued" or not listed in either this specification or on the aforementioned page must be rejected as invalid. Conformance checkers may cache this information (e.g. for performance reasons or to avoid the use of unreliable network connectivity).

When an author uses a new metadata name not defined by either this specification or the Wiki page, conformance checkers should offer to add the value to the Wiki, with the details described above, with the "proposed" status.

Metadata names whose values are to be URLs must not be proposed or accepted. Links must be represented using the link element, not the meta element.

4.2.5.3 Pragma directives

When the http-equiv attribute is specified on a meta element, the element is a pragma directive.

The http-equiv attribute is an enumerated attribute. The following table lists the keywords defined for this attribute. The states given in the first cell of the rows with keywords give the states to which those keywords map. Some of the keywords are non-conforming, as noted in the last column.

State	Keyword	Notes
Content Language	`content-language`	Non-conforming
Encoding declaration	`content-type`
Default style	`default-style`
Refresh	`refresh`
Cookie setter	`set-cookie`	Non-conforming
X-UA-Compatible	`x-ua-compatible`
Content security policy	`Content-Security-Policy`

When a meta element is inserted into the document, if its http-equiv attribute is present and represents one of the above states, then the user agent must run the algorithm appropriate for that state, as described in the following list:

Content language state (http-equiv="content-language")

This feature is non-conforming. Authors are encouraged to use the lang attribute instead.

This pragma sets the pragma-set default language. Until such a pragma is successfully processed, there is no pragma-set default language.

If the meta element has no content attribute, then abort these steps.
If the element's content attribute contains a U+002C COMMA character (,) then abort these steps.
Let input be the value of the element's content attribute.
Let position point at the first character of input.
Skip whitespace.
Collect a sequence of characters that are not space characters.
Let candidate be the string that resulted from the previous step.
If candidate is the empty string, abort these steps.
Set the pragma-set default language to candidate.

If the value consists of multiple space-separated tokens, tokens after the first are ignored.

This pragma is almost, but not quite, entirely unlike the HTTP `Content-Language` header of the same name. [HTTP]

Encoding declaration state (http-equiv="content-type")

The Encoding declaration state is just an alternative form of setting the charset attribute: it is a character encoding declaration. This state's user agent requirements are all handled by the parsing section of the specification.

For meta elements with an http-equiv attribute in the Encoding declaration state, the content attribute must have a value that is an ASCII case-insensitive match for a string that consists of: the literal string "text/html;", optionally followed by any number of space characters, followed by the literal string "charset=", followed by one of the labels of the character encoding of the character encoding declaration.

A document must not contain both a meta element with an http-equiv attribute in the Encoding declaration state and a meta element with the charset attribute present.

The Encoding declaration state may be used in HTML documents, but elements with an http-equiv attribute in that state must not be used in XML documents.

Default style state (http-equiv="default-style")

This pragma sets the name of the default alternative style sheet set.

If the meta element has no content attribute, or if that attribute's value is the empty string, then abort these steps.
Set the preferred style sheet set to the value of the element's content attribute. [CSSOM]

Refresh state (http-equiv="refresh")

This pragma acts as timed redirect.

If another meta element with an http-equiv attribute in the Refresh state has already been successfully processed (i.e. when it was inserted the user agent processed it and reached the last step of this list of steps), then abort these steps.
If the meta element has no content attribute, or if that attribute's value is the empty string, then abort these steps.
Let input be the value of the element's content attribute.
Let position point at the first character of input.
Skip whitespace.
Collect a sequence of characters that are ASCII digits, and parse the resulting string using the rules for parsing non-negative integers. If the sequence of characters collected is the empty string, then no number will have been parsed; abort these steps. Otherwise, let time be the parsed number.
Collect a sequence of characters that are ASCII digits and U+002E FULL STOP characters (.). Ignore any collected characters.
Skip whitespace.
Let url be the address of the current page.
If the character in input pointed to by position is a U+003B SEMICOLON character (;) or a U+002C COMMA character (,), then advance position to the next character. Otherwise, jump to the last step.
Skip whitespace.
If the character in input pointed to by position is a U+0055 LATIN CAPITAL LETTER U character (U) or a U+0075 LATIN SMALL LETTER U character (u), then advance position to the next character. Otherwise, jump to the last step.
If the character in input pointed to by position is a U+0052 LATIN CAPITAL LETTER R character (R) or a U+0072 LATIN SMALL LETTER R character (r), then advance position to the next character. Otherwise, jump to the last step.
If the character in input pointed to by position is s U+004C LATIN CAPITAL LETTER L character (L) or a U+006C LATIN SMALL LETTER L character (l), then advance position to the next character. Otherwise, jump to the last step.
Skip whitespace.
If the character in input pointed to by position is a U+003D EQUALS SIGN (=), then advance position to the next character. Otherwise, jump to the last step.
Skip whitespace.
If the character in input pointed to by position is either a U+0027 APOSTROPHE character (') or U+0022 QUOTATION MARK character ("), then let quote be that character, and advance position to the next character. Otherwise, let quote be the empty string.
Let url be equal to the substring of input from the character at position to the end of the string.
If quote is not the empty string, and there is a character in url equal to quote, then truncate url at that character, so that it and all subsequent characters are removed.
Strip any trailing space characters from the end of url.
Strip any U+0009 CHARACTER TABULATION (tab), U+000A LINE FEED (LF), and U+000D CARRIAGE RETURN (CR) characters from url.
Resolve the url value to an absolute URL, relative to the meta element. If this fails, abort these steps.
Perform one or more of the following steps:
- After the refresh has come due (as defined below), if the user has not canceled the redirect and if the meta element's node document's active sandboxing flag set does not have the sandboxed automatic features browsing context flag set, navigate the Document's browsing context to url, with replacement enabled, and with the Document's browsing context as the source browsing context.
  
  For the purposes of the previous paragraph, a refresh is said to have come due as soon as the later of the following two conditions occurs:
  - At least time seconds have elapsed since the document has completely loaded, adjusted to take into account user or user agent preferences.
  - At least time seconds have elapsed since the meta element was inserted into the Document, adjusted to take into account user or user agent preferences.
- Provide the user with an interface that, when selected, navigates a browsing context to url, with the Document's browsing context as the source browsing context.
- Do nothing.
In addition, the user agent may, as with anything, inform the user of any and all aspects of its operation, including the state of any timers, the destinations of any timed redirects, and so forth.

For meta elements with an http-equiv attribute in the Refresh state, the content attribute must have a value consisting either of:

just a valid non-negative integer, or
a valid non-negative integer, followed by a U+003B SEMICOLON character (;), followed by one or more space characters, followed by a substring that is an ASCII case-insensitive match for the string "URL", followed by a U+003D EQUALS SIGN character (=), followed by a valid URL that does not start with a literal U+0027 APOSTROPHE (') or U+0022 QUOTATION MARK (") character.

In the former case, the integer represents a number of seconds before the page is to be reloaded; in the latter case the integer represents a number of seconds before the page is to be replaced by the page at the given URL.

A news organization's front page could include the following markup in the page's head element, to ensure that the page automatically reloads from the server every five minutes:

<meta http-equiv="Refresh" content="300">

A sequence of pages could be used as an automated slide show by making each page refresh to the next page in the sequence, using markup such as the following:

<meta http-equiv="Refresh" content="20; URL=page4.html">

Cookie setter (http-equiv="set-cookie")

This pragma sets an HTTP cookie. [COOKIES]

It is non-conforming. Real HTTP headers should be used instead.

If the meta element has no content attribute, or if that attribute's value is the empty string, then abort these steps.
Obtain the storage mutex.
Act as if receiving a set-cookie-string for the document's address via a "non-HTTP" API, consisting of the value of the element's content attribute encoded as UTF-8. [COOKIES] [ENCODING]

X-UA-Compatible state (http-equiv="x-ua-compatible")

In practice, this pragma encourages Internet Explorer to more closely follow the specifications.

For meta elements with an http-equiv attribute in the X-UA-Compatible state, the content attribute must have a value that is an ASCII case-insensitive match for the string "IE=edge".

User agents are required to ignore this pragma.

Content security policy state (http-equiv="content-security-policy")

This pragma enforces a Content Security Policy on a Document. [CSP]

If the meta element is not a child of a head element, abort these steps.
If the meta element has no content attribute, or if that attribute's value is the empty string, then abort these steps.
Let policy be the result of executing Content Security Policy's parse the policy algorithm on the meta element's content attribute's value.
Remove all occurrences of the reflected-xss, report-uri, frame-ancestors, and sandbox directives from policy.
Enforce the policy policy.

For meta elements with an http-equiv attribute in the Content security policy state, the content attribute must have a value consisting of a valid Content Security Policy, which will be enforced upon the current document. [CSP]

A page might choose to mitigate the risk of cross-site scripting attacks by preventing the execution of inline JavaScript, as well as blocking all plugin content, using a policy such as the following:

<meta http-equiv="Content-Security-Policy" content="script-src 'self'; object-src 'none'">

There must not be more than one meta element with any particular state in the document at a time.

4.2.5.4 Other pragma directives

Extensions to the predefined set of pragma directives may, under certain conditions, be registered in the WHATWG Wiki PragmaExtensions page. [WHATWGWIKI]

Such extensions must use a name that is identical to an HTTP header registered in the Permanent Message Header Field Registry, and must have behaviour identical to that described for the HTTP header. [IANAPERMHEADERS]

Pragma directives corresponding to headers describing metadata, or not requiring specific user agent processing, must not be registered; instead, use metadata names. Pragma directives corresponding to headers that affect the HTTP processing model (e.g. caching) must not be registered, as they would result in HTTP-level behaviour being different for user agents that implement HTML than for user agents that do not.

Anyone is free to edit the WHATWG Wiki PragmaExtensions page at any time to add a pragma directive satisfying these conditions. Such registrations must specify the following information:

Keyword: The actual name being defined. The name must match a previously-registered HTTP name with the same requirements.
Brief description: A short non-normative description of the purpose of the pragma directive.
Specification: A link to the specification defining the corresponding HTTP header.

Conformance checkers must use the information given on the WHATWG Wiki PragmaExtensions page to establish if a value is allowed or not: values defined in this specification or listed on the aforementioned page must be accepted, whereas values not listed in either this specification or on the aforementioned page must be rejected as invalid. Conformance checkers may cache this information (e.g. for performance reasons or to avoid the use of unreliable network connectivity).

4.2.5.5 Specifying the document's character encoding

A character encoding declaration is a mechanism by which the character encoding used to store or transmit a document is specified.

The following restrictions apply to character encoding declarations:

The character encoding name given must be an ASCII case-insensitive match for one of the labels of the character encoding used to serialise the file. [ENCODING]
The character encoding declaration must be serialised without the use of character references or character escapes of any kind.
The element containing the character encoding declaration must be serialised completely within the first 1024 bytes of the document.

In addition, due to a number of restrictions on meta elements, there can only be one meta-based character encoding declaration per document.

If an HTML document does not start with a BOM, and its encoding is not explicitly given by Content-Type metadata, and the document is not an iframe srcdoc document, then the character encoding used must be an ASCII-compatible encoding, and the encoding must be specified using a meta element with a charset attribute or a meta element with an http-equiv attribute in the Encoding declaration state.

A character encoding declaration is required (either in the Content-Type metadata or explicitly in the file) even if the encoding is US-ASCII, because a character encoding is needed to process non-ASCII characters entered by the user in forms, in URLs generated by scripts, and so forth.

If the document is an iframe srcdoc document, the document must not have a character encoding declaration. (In this case, the source is already decoded, since it is part of the document that contained the iframe.)

If an HTML document contains a meta element with a charset attribute or a meta element with an http-equiv attribute in the Encoding declaration state, then the character encoding used must be an ASCII-compatible encoding.

Authors should use UTF-8. Conformance checkers may advise authors against using legacy encodings. [ENCODING]

Authoring tools should default to using UTF-8 for newly-created documents. [ENCODING]

Authors must not use encodings that are not defined in the WHATWG Encoding standard. Additionally, authors should not use ISO-2022-JP. [ENCODING]

Some encodings that are not defined in the WHATWG Encoding standard use bytes in the range 0x20 to 0x7E, inclusive, to encode characters other than the corresponding characters in the range U+0020 to U+007E, inclusive, and represent a potential security vulnerability: A user agent might end up interpreting supposedly benign plain text content as HTML tags and JavaScript.

Using non-UTF-8 encodings can have unexpected results on form submission and URL encodings, which use the document's character encoding by default.

In XHTML, the XML declaration should be used for inline character encoding information, if necessary.

In HTML, to declare that the character encoding is UTF-8, the author could include the following markup near the top of the document (in the head element):

<meta charset="utf-8">

In XML, the XML declaration would be used instead, at the very top of the markup:

<?xml version="1.0" encoding="utf-8"?>

4.2.6 The `style` element

If the scoped attribute is present: flow content.

If the scoped attribute is absent: where metadata content is expected.

If the scoped attribute is absent: in a noscript element that is a child of a head element.

If the scoped attribute is present: where flow content is expected, but before any other flow content other than inter-element whitespace and style elements, and not as the child of an element whose content model is transparent.

Depends on the value of the type attribute, but must match requirements described in prose below.

Neither tag is omissible.

media — Applicable media

nonce — Cryptographic nonce used in Content Security Policy checks [CSP]

type — Type of embedded resource

scoped — Whether the styles apply to the entire document or just the parent subtree

Also, the title attribute has special semantics on this element: Alternative style sheet set name.

Allowed ARIA role attribute values:

None

interface HTMLStyleElement : HTMLElement {
  attribute DOMString media;
  attribute DOMString nonce;
  attribute DOMString type;
  attribute boolean scoped;
};
HTMLStyleElement implements LinkStyle;

The style element allows authors to embed style information in their documents. The style element is one of several inputs to the styling processing model. The element does not represent content for the user.

The type attribute gives the styling language. If the attribute is present, its value must be a valid MIME type that designates a styling language. The charset parameter must not be specified. The default value for the type attribute, which is used if the attribute is absent, is "text/css". [RFC2318]

When examining types to determine if they support the language, user agents must not ignore unknown MIME parameters — types with unknown parameters must be assumed to be unsupported. The charset parameter must be treated as an unknown parameter for the purpose of comparing MIME types here.

The media attribute says which media the styles apply to. The value must be a valid media query list. The user agent must apply the styles when the media attribute's value matches the environment and the other relevant conditions apply, and must not apply them otherwise.

The styles might be further limited in scope, e.g. in CSS with the use of @media blocks. This specification does not override such further restrictions or requirements.

The default, if the media attribute is omitted, is "all", meaning that by default styles apply to all media.

The nonce attribute represents a cryptographic nonce ("number used once") which can be used by Content Security Policy to determine whether or not the style specified by an element will be applied to the document. The value is text. [CSP]

The processing model for the nonce attribute needs to be integrated into the update a style block algorithm. The current definition in [CSP] is fairly vague. See w3c/webappsec#463.

The scoped attribute is a boolean attribute. If present, it indicates that the styles are intended just for the subtree rooted at the style element's parent element, as opposed to the whole Document.

If the scoped attribute is present and the element has a parent element, then the style element must precede any flow content in its parent element other than inter-element whitespace and other style elements, and the parent element's content model must not have a transparent component.

This implies that scoped style elements cannot be children of, e.g., a or ins elements, even when those are used as flow content containers.

A style element without a scoped attribute is restricted to appearing in the head of the document.

A style sheet declared by a style element that has a scoped attribute and has a parent node that is an element is scoped, with the scoping root being the style element's parent element. [CSSSCOPED]

The title attribute on style elements defines alternative style sheet sets. If the style element has no title attribute, then it has no title; the title attribute of ancestors does not apply to the style element. [CSSOM]

The title attribute on style elements, like the title attribute on link elements, differs from the global title attribute in that a style block without a title does not inherit the title of the parent element: it merely has no title.

The textContent of a style element must match the style production in the following ABNF, the character set for which is Unicode. [ABNF]

style         = no-c-start *( c-start no-c-end c-end no-c-start )
no-c-start    = < any string that doesn't contain a substring that matches c-start >
c-start       = "<!--"
no-c-end      = < any string that doesn't contain a substring that matches c-end >
c-end         = "-->"

Whenever one of the following conditions occur for an element whose Document is in a browsing context:

the element is popped off the stack of open elements of an HTML parser or XML parser,
the element is not on the stack of open elements of an HTML parser or XML parser, and it is inserted into a document or removed from a document,
the element is not on the stack of open elements of an HTML parser or XML parser, and one of its child nodes is modified by a script,

...the user agent must run the update a style block algorithm that applies for the style sheet language specified by the element's type attribute, passing it the element's style data.

For styling languages that consist of pure text (as opposed to XML), a style element's style data is the concatenation of the contents of all the Text nodes that are children of the style element (not any other nodes such as comments or elements), in tree order. For XML-based styling languages, the style data consists of all the child nodes of the style element.

The update a style block algorithm for CSS (text/css) is as follows:

Let element be the style element.
If element has an associated CSS style sheet, remove the CSS style sheet in question.
If element is not in a Document, then abort these steps.
Create a CSS style sheet with the following properties:

type
text/css
owner node
element
media

The media attribute of element.

This is a reference to the (possibly absent at this time) attribute, rather than a copy of the attribute's current value. The CSSOM specification defines what happens when the attribute is dynamically set, changed, or removed.

title

The title attribute of element.

Again, this is a reference to the attribute.

alternate flag
Unset.
origin-clean flag
Set.
location
parent CSS style sheet
owner CSS rule
null
disabled flag
Left at its default value.
CSS rules
Left uninitialised.

This specification does not define any other styling language's update a style block algorithm.

Once the attempts to obtain the style sheet's critical subresources, if any, are complete, or, if the style sheet has no critical subresources, once the style sheet has been parsed and processed, the user agent must, if the loads were successful or there were none, queue a task to fire a simple event named load at the style element, or, if one of the style sheet's critical subresources failed to completely load for any reason (e.g. DNS error, HTTP 404 response, a connection being prematurely closed, unsupported Content-Type), queue a task to fire a simple event named error at the style element. Non-network errors in processing the style sheet or its subresources (e.g. CSS parse errors, PNG decoding errors) are not failures for the purposes of this paragraph.

The task source for these tasks is the DOM manipulation task source.

The element must delay the load event of the element's node document until all the attempts to obtain the style sheet's critical subresources, if any, are complete.

This specification does not specify a style system, but CSS is expected to be supported by most Web browsers. [CSS]

The media, nonce, type and scoped IDL attributes must reflect the respective content attributes of the same name.

The LinkStyle interface is also implemented by this element. [CSSOM]

The following document has its stress emphasis styled as bright red text rather than italics text, while leaving titles of works and Latin words in their default italics. It shows how using appropriate elements enables easier restyling of documents.

<!DOCTYPE html>
<html lang="en-US">
 <head>
  <title>My favorite book</title>
  <style>
   body { color: black; background: white; }
   em { font-style: normal; color: red; }
  </style>
 </head>
 <body>
  <p>My <em>favorite</em> book of all time has <em>got</em> to be
  <cite>A Cat's Life</cite>. It is a book by P. Rahmel that talks
  about the <i lang="la">Felis Catus</i> in modern human society.</p>
 </body>
</html>

4.2.7 Interactions of styling and scripting

Style sheets, whether added by a link element, a style element, an <?xml-stylesheet?> PI, an HTTP `Link` header, or some other mechanism, have a style sheet ready flag, which is initially unset.

When a style sheet is ready to be applied, its style sheet ready flag must be set. If the style sheet referenced no other resources (e.g. it was an internal style sheet given by a style element with no @import rules), then the style rules must be immediately made available to script; otherwise, the style rules must only be made available to script once the event loop reaches its update the rendering step.

A style sheet in the context of the Document of an HTML parser or XML parser is said to be a style sheet that is blocking scripts if the element was created by that Document's parser, and the element is either a style element or a link element that was an external resource link that contributes to the styling processing model when the element was created by the parser, and the element's style sheet was enabled when the element was created by the parser, and the element's style sheet ready flag is not yet set, and, the last time the event loop reached step 1, the element was in that Document, and the user agent hasn't given up on that particular style sheet yet. A user agent may give up on a style sheet at any time.

Giving up on a style sheet before the style sheet loads, if the style sheet eventually does still load, means that the script might end up operating with incorrect information. For example, if a style sheet sets the colour of an element to green, but a script that inspects the resulting style is executed before the sheet is loaded, the script will find that the element is black (or whatever the default colour is), and might thus make poor choices (e.g. deciding to use black as the colour elsewhere on the page, instead of green). Implementors have to balance the likelihood of a script using incorrect information with the performance impact of doing nothing while waiting for a slow network request to finish.

A Document has a style sheet that is blocking scripts if there is either a style sheet that is blocking scripts in the context of that Document, or if that Document is in a browsing context that has a parent browsing context, and the active document of that parent browsing context itself has a style sheet that is blocking scripts.

A Document has no style sheet that is blocking scripts if it does not have a style sheet that is blocking scripts as defined in the previous paragraph.

4.3 Sections

4.3.1 The `body` element

Sectioning root.

As the second element in an html element.

A body element's start tag can be omitted if the element is empty, or if the first thing inside the body element is not a space character or a comment, except if the first thing inside the body element is a meta, link, script, style, or template element.

A body element's end tag can be omitted if the body element is not immediately followed by a comment.

onafterprint

onbeforeprint

onbeforeunload

onhashchange

onlanguagechange

onmessage

onoffline

ononline

onpagehide

onpageshow

onpopstate

onstorage

onunload

Allowed ARIA role attribute values:

document role (default - do not set), application.

Any aria-* attributes applicable to the allowed roles.

interface HTMLBodyElement : HTMLElement {

  // also has obsolete members
};
HTMLBodyElement implements WindowEventHandlers;

The body element represents the content of the document.

In conforming documents, there is only one body element. The document.body IDL attribute provides scripts with easy access to a document's body element.

Some DOM operations (for example, parts of the drag and drop model) are defined in terms of "the body element". This refers to a particular element in the DOM, as per the definition of the term, and not any arbitrary body element.

The body element exposes as event handler content attributes a number of the event handlers of the Window object. It also mirrors their event handler IDL attributes.

The onblur, onerror, onfocus, onload, onresize, and onscroll event handlers of the Window object, exposed on the body element, replace the generic event handlers with the same names normally supported by HTML elements.

Thus, for example, a bubbling error event dispatched on a child of the body element of a Document would first trigger the onerror event handler content attributes of that element, then that of the root html element, and only then would it trigger the onerror event handler content attribute on the body element. This is because the event would bubble from the target, to the body, to the html, to the Document, to the Window, and the event handler on the body is watching the Window not the body. A regular event listener attached to the body using addEventListener(), however, would be run when the event bubbled through the body and not when it reaches the Window object.

This page updates an indicator to show whether or not the user is online:

<!DOCTYPE HTML>
<html>
 <head>
  <title>Online or offline?</title>
  <script>
   function update(online) {
     document.getElementById('status').textContent =
       online ? 'Online' : 'Offline';
   }
  </script>
 </head>
 <body ononline="update(true)"
       onoffline="update(false)"
       onload="update(navigator.onLine)">
  <p>You are: <span id="status">(Unknown)</span></p>
 </body>
</html>

4.3.2 The `article` element

Categories:: Flow content.; Sectioning content.; Palpable content.
Contexts in which this element can be used:: Where flow content is expected.
Content model:: Flow content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: article (default - do not set), application, document or main.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The article element represents a complete, or self-contained, composition in a document, page, application, or site and that is, in principle, independently distributable or reusable, e.g. in syndication. This could be a forum post, a magazine or newspaper article, a blog entry, a user-submitted comment, an interactive widget or gadget, or any other independent item of content. Each article should be identified, typically by including a heading (h1–h6 element) as a child of the article element.

When article elements are nested, the inner article elements represent articles that are in principle related to the contents of the outer article. For instance, a blog entry on a site that accepts user-submitted comments could represent the comments as article elements nested within the article element for the blog entry.

Author information associated with an article element (q.v. the address element) does not apply to nested article elements.

When used specifically with content to be redistributed in syndication, the article element is similar in purpose to the entry element in Atom. [ATOM]

The schema.org microdata vocabulary can be used to provide the publication date for an article element, using one of the CreativeWork subtypes.

When the main content of the page (i.e. excluding footers, headers, navigation blocks, and sidebars) is all one single self-contained composition, that content may be marked with an article, but it is technically redundant in that case (since it's self-evident that the page is a single composition, as it is a single document).

This example shows a blog post using the article element, with some schema.org annotations:

<article itemscope itemtype="http://schema.org/BlogPosting">
 <header>
  <h1 itemprop="headline">The Very First Rule of Life</h1>
  <p><time itemprop="datePublished" datetime="2009-10-09">3 days ago</time></p>
  <link itemprop="url" href="?comments=0">
 </header>
 <p>If there's a microphone anywhere near you, assume it's hot and
 sending whatever you're saying to the world. Seriously.</p>
 <p>...</p>
 <footer>
  <a itemprop="discussionUrl" href="?comments=1">Show comments...</a>
 </footer>
</article>

Here is that same blog post, but showing some of the comments:

<article itemscope itemtype="http://schema.org/BlogPosting">
 <header>
  <h1 itemprop="headline">The Very First Rule of Life</h1>
  <p><time itemprop="datePublished" datetime="2009-10-09">3 days ago</time></p>
  <link itemprop="url" href="?comments=0">
 </header>
 <p>If there's a microphone anywhere near you, assume it's hot and
 sending whatever you're saying to the world. Seriously.</p>
 <p>...</p>
 <section>
  <h1>Comments</h1>
  <article itemprop="comment" itemscope itemtype="http://schema.org/UserComments" id="c1">
   <link itemprop="url" href="#c1">
   <footer>
    <p>Posted by: <span itemprop="creator" itemscope itemtype="http://schema.org/Person">
     <span itemprop="name">George Washington</span>
    </span></p>
    <p><time itemprop="commentTime" datetime="2009-10-10">15 minutes ago</time></p>
   </footer>
   <p>Yeah! Especially when talking about your lobbyist friends!</p>
  </article>
  <article itemprop="comment" itemscope itemtype="http://schema.org/UserComments" id="c2">
   <link itemprop="url" href="#c2">
   <footer>
    <p>Posted by: <span itemprop="creator" itemscope itemtype="http://schema.org/Person">
     <span itemprop="name">George Hammond</span>
    </span></p>
    <p><time itemprop="commentTime" datetime="2009-10-10">5 minutes ago</time></p>
   </footer>
   <p>Hey, you have the same first name as me.</p>
  </article>
 </section>
</article>

Notice the use of footer to give the information for each comment (such as who wrote it and when): the footer element can appear at the start of its section when appropriate, such as in this case. (Using header in this case wouldn't be wrong either; it's mostly a matter of authoring preference.)

In this example, article elements are used to host widgets on a portal page.

<!DOCTYPE HTML>
<title>eHome Portal</title>
<link rel=stylesheet href="/styles/main.css">
<article>
 <style scoped> @import url(/widgets/stocks/look.css); </style>
 <script src="/widgets/stocks/core.js"></script>
 <h1>Stocks</h1>
 <table>
  <thead> <tr> <th> Stock <th> Value <th> Delta
  <tbody> <template> <tr> <td> <td> <td> </template>
 </table>
 <p> <input type=button value="Refresh" onclick="stocks.refresh()">
</article>
<article>
 <style scoped> @import url(/widgets/news/look.css); </style>
 <script src="/widgets/news/core.js"></script>
 <h1>News</h1>
 <ul>
  <template>
   <li>
    <p><img> <strong></strong>
    <p>
  </template>
 </ul>
 <p> <input type=button value="Refresh" onclick="news.refresh()">
</article>

4.3.3 The `section` element

Categories:: Flow content.; Sectioning content.; Palpable content.
Contexts in which this element can be used:: Where flow content is expected.
Content model:: Flow content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: region role (default - do not set), alert, alertdialog, application, contentinfo, dialog, document, log, main, marquee, presentation, search or status.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The section element represents a generic section of a document or application. A section, in this context, is a thematic grouping of content. Each section should be identified, typically by including a heading ( h1- h6 element) as a child of the section element.

Examples of sections would be chapters, the various tabbed pages in a tabbed dialog box, or the numbered sections of a thesis. A Web site's home page could be split into sections for an introduction, news items, and contact information.

Authors are encouraged to use the article element instead of the section element when it would make sense to syndicate the contents of the element.

The section element is not a generic container element. When an element is needed only for styling purposes or as a convenience for scripting, authors are encouraged to use the div element instead. A general rule is that the section element is appropriate only if the element's contents would be listed explicitly in the document's outline.

Here is a graduation programme with two sections, one for the list of people graduating, and one for the description of the ceremony. (The markup in this example features an uncommon style sometimes used to minimise the amount of inter-element whitespace.)

<!DOCTYPE Html>
<Html
 ><Head
   ><Title
     >Graduation Ceremony Summer 2022</Title
   ></Head
 ><Body
   ><H1
     >Graduation</H1
   ><Section
     ><H1
       >Ceremony</H1
     ><P
       >Opening Procession</P
     ><P
       >Speech by Validactorian</P
     ><P
       >Speech by Class President</P
     ><P
       >Presentation of Diplomas</P
     ><P
       >Closing Speech by Headmaster</P
   ></Section
   ><Section
     ><H1
       >Graduates</H1
     ><Ul
       ><Li
         >Molly Carpenter</Li
       ><Li
         >Anastasia Luccio</Li
       ><Li
         >Ebenezar McCoy</Li
       ><Li
         >Karrin Murphy</Li
       ><Li
         >Thomas Raith</Li
       ><Li
         >Susan Rodriguez</Li
     ></Ul
   ></Section
 ></Body
></Html>

4.3.4 The `nav` element

Categories:: Flow content.; Sectioning content.; Palpable content.
Contexts in which this element can be used:: Where flow content is expected.
Content model:: Flow content, but with no main element descendants.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: navigation role (default - do not set) or presentation.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The nav element represents a section of a page that links to other pages or to parts within the page: a section with navigation links.

In cases where the content of a nav element represents a list of items, use list markup to aid understanding and navigation.

Not all groups of links on a page need to be in a nav element — the element is primarily intended for sections that consist of major navigation blocks. In particular, it is common for footers to have a short list of links to various pages of a site, such as the terms of service, the home page, and a copyright page. The footer element alone is sufficient for such cases; while a nav element can be used in such cases, it is usually unnecessary.

User agents (such as screen readers) that are targeted at users who can benefit from navigation information being omitted in the initial rendering, or who can benefit from navigation information being immediately available, can use this element as a way to determine what content on the page to initially skip or provide on request (or both).

In the following example, there are two nav elements, one for primary navigation around the site, and one for secondary navigation around the page itself.

<body>
 <h1>The Wiki Center Of Exampland</h1>
 <nav>
  <ul>
   <li><a href="/">Home</a></li>
   <li><a href="/events">Current Events</a></li>
   ...more...
  </ul>
 </nav>
 <article>
  <header>
   <h1>Demos in Exampland</h1>
   <p>Written by A. N. Other.</p>
  </header>
  <nav>
   <ul>
    <li><a href="#public">Public demonstrations</a></li>
    <li><a href="#destroy">Demolitions</a></li>
    ...more...
   </ul>
  </nav>
  <div>
   <section id="public">
    <h1>Public demonstrations</h1>
    <p>...more...</p>
   </section>
   <section id="destroy">
    <h1>Demolitions</h1>
    <p>...more...</p>
   </section>
   ...more...
  </div>
  <footer>
   <p><a href="?edit">Edit</a> | <a href="?delete">Delete</a> | <a href="?Rename">Rename</a></p>
  </footer>
 </article>
 <footer>
  <p><small>© copyright 1998 Exampland Emperor</small></p>
 </footer>
</body>

In the following example, the page has several places where links are present, but only one of those places is considered a navigation section.

<body itemscope itemtype="http://schema.org/Blog">
 <header>
  <h1>Wake up sheeple!</h1>
  <p><a href="news.html">News</a> -
     <a href="blog.html">Blog</a> -
     <a href="forums.html">Forums</a></p>
  <p>Last Modified: <span itemprop="dateModified">2009-04-01</span></p>
  <nav>
   <h1>Navigation</h1>
   <ul>
    <li><a href="articles.html">Index of all articles</a></li>
    <li><a href="today.html">Things sheeple need to wake up for today</a></li>
    <li><a href="successes.html">Sheeple we have managed to wake</a></li>
   </ul>
  </nav>
 </header>
 <main>
  <article itemprop="blogPosts" itemscope itemtype="http://schema.org/BlogPosting">
   <header>
    <h1 itemprop="headline">My Day at the Beach</h1>
   </header>
   <main itemprop="articleBody">
    <p>Today I went to the beach and had a lot of fun.</p>
    ...more content...
   </main>
   <footer>
    <p>Posted <time itemprop="datePublished" datetime="2009-10-10">Thursday</time>.</p>
   </footer>
  </article>
  ...more blog posts...
 </main>
 <footer>
  <p>Copyright ©
   <span itemprop="copyrightYear">2010</span>
   <span itemprop="copyrightHolder">The Example Company</span>
  </p>
  <p><a href="about.html">About</a> -
     <a href="policy.html">Privacy Policy</a> -
     <a href="contact.html">Contact Us</a></p>
 </footer>
</body>

Notice the main elements being used to wrap all the contents of the page other than the header and footer, and all the contents of the blog entry other than its header and footer.

You can also see microdata annotations in the above example that use the schema.org vocabulary to provide the publication date and other metadata about the blog post.

A nav element doesn't have to contain a list, it can contain other kinds of content as well. In this navigation block, links are provided in prose:

<nav>
 <h1>Navigation</h1>
 <p>You are on my home page. To the north lies <a href="/blog">my
 blog</a>, from whence the sounds of battle can be heard. To the east
 you can see a large mountain, upon which many <a
 href="/school">school papers</a> are littered. Far up thus mountain
 you can spy a little figure who appears to be me, desperately
 scribbling a <a href="/school/thesis">thesis</a>.</p>
 <p>To the west are several exits. One fun-looking exit is labeled <a
 href="http://games.example.com/">"games"</a>. Another more
 boring-looking exit is labeled <a
 href="http://isp.example.net/">ISP™</a>.</p>
 <p>To the south lies a dark and dank <a href="/about">contacts
 page</a>. Cobwebs cover its disused entrance, and at one point you
 see a rat run quickly out of the page.</p>
</nav>

In this example, nav is used in an e-mail application, to let the user switch folders:

<p><input type=button value="Compose" onclick="compose()"></p>
<nav>
 <h1>Folders</h1>
 <ul>
  <li> <a href="/inbox" onclick="return openFolder(this.href)">Inbox</a> <span class=count></span>
  <li> <a href="/sent" onclick="return openFolder(this.href)">Sent</a>
  <li> <a href="/drafts" onclick="return openFolder(this.href)">Drafts</a>
  <li> <a href="/trash" onclick="return openFolder(this.href)">Trash</a>
  <li> <a href="/customers" onclick="return openFolder(this.href)">Customers</a>
 </ul>
</nav>

4.3.5 The `aside` element

Categories:: Flow content.; Sectioning content.; Palpable content.
Contexts in which this element can be used:: Where flow content is expected.
Content model:: Flow content, but with no main element descendants.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: complementary role (default - do not set), note, search or presentation.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The aside element represents a section of a page that consists of content that is tangentially related to the content around the aside element, and which could be considered separate from that content. Such sections are often represented as sidebars in printed typography.

The element can be used for typographical effects like pull quotes or sidebars, for advertising, for groups of nav elements, and for other content that is considered separate from the main content of the page.

It's not appropriate to use the aside element just for parentheticals, since those are part of the main flow of the document.

The following example shows how an aside is used to mark up background material on Switzerland in a much longer news story on Europe.

<aside>
 <h1>Switzerland</h1>
 <p>Switzerland, a land-locked country in the middle of geographic
 Europe, has not joined the geopolitical European Union, though it is
 a signatory to a number of European treaties.</p>
</aside>

The following example shows how an aside is used to mark up a pull quote in a longer article.

...

<p>He later joined a large company, continuing on the same work.
<q>I love my job. People ask me what I do for fun when I'm not at
work. But I'm paid to do my hobby, so I never know what to
answer. Some people wonder what they would do if they didn't have to
work... but I know what I would do, because I was unemployed for a
year, and I filled that time doing exactly what I do now.</q></p>

<aside>
 <q> People ask me what I do for fun when I'm not at work. But I'm
 paid to do my hobby, so I never know what to answer. </q>
</aside>

<p>Of course his work — or should that be hobby? —
isn't his only passion. He also enjoys other pleasures.</p>

...

The following extract shows how aside can be used for blogrolls and other side content on a blog:

<body>
 <header>
  <h1>My wonderful blog</h1>
  <p>My tagline</p>
 </header>
 <aside>
  <!-- this aside contains two sections that are tangentially related
  to the page, namely, links to other blogs, and links to blog posts
  from this blog -->
  <nav>
   <h1>My blogroll</h1>
   <ul>
    <li><a href="http://blog.example.com/">Example Blog</a>
   </ul>
  </nav>
  <nav>
   <h1>Archives</h1>
   <ol reversed>
    <li><a href="/last-post">My last post</a>
    <li><a href="/first-post">My first post</a>
   </ol>
  </nav>
 </aside>
 <aside>
  <!-- this aside is tangentially related to the page also, it
  contains twitter messages from the blog author -->
  <h1>Twitter Feed</h1>
  <blockquote cite="http://twitter.example.net/t31351234">
   I'm on vacation, writing my blog.
  </blockquote>
  <blockquote cite="http://twitter.example.net/t31219752">
   I'm going to go on vacation soon.
  </blockquote>
 </aside>
 <article>
  <!-- this is a blog post -->
  <h1>My last post</h1>
  <p>This is my last post.</p>
  <footer>
   <p><a href="/last-post" rel=bookmark>Permalink</a>
  </footer>
 </article>
 <article>
  <!-- this is also a blog post -->
  <h1>My first post</h1>
  <p>This is my first post.</p>
  <aside>
   <!-- this aside is about the blog post, since it's inside the
   <article> element; it would be wrong, for instance, to put the
   blogroll here, since the blogroll isn't really related to this post
   specifically, only to the page as a whole -->
   <h1>Posting</h1>
   <p>While I'm thinking about it, I wanted to say something about
   posting. Posting is fun!</p>
  </aside>
  <footer>
   <p><a href="/first-post" rel=bookmark>Permalink</a>
  </footer>
 </article>
 <footer>
  <nav>
   <a href="/archives">Archives</a> —
   <a href="/about">About me</a> —
   <a href="/copyright">Copyright</a>
  </nav>
 </footer>
</body>

4.3.6 The `h1`, `h2`, `h3`, `h4`, `h5`, and `h6` elements

Where flow content is expected.

Neither tag is omissible.

Allowed ARIA role attribute values:

heading role (default - do not set), tab or presentation.

Any aria-* attributes applicable to the allowed roles.

interface HTMLHeadingElement : HTMLElement {
  // also has obsolete members
};

These elements represent headings for their sections.

The semantics and meaning of these elements are defined in the section on headings and sections.

These elements have a rank given by the number in their name. The h1 element is said to have the highest rank, the h6 element has the lowest rank, and two elements with the same name have equal rank.

h1–h6 elements must not be used to markup subheadings, subtitles, alternative titles and taglines unless intended to be the heading for a new section or subsection. Instead use the markup patterns in the Common idioms without dedicated elements section of the specification.

As far as their respective document outlines (their heading and section structures) are concerned, these two snippets are semantically equivalent:

<body>
<h1>Let's call it a draw(ing surface)</h1>
<h2>Diving in</h2>
<h2>Simple shapes</h2>
<h2>Canvas coordinates</h2>
<h3>Canvas coordinates diagram</h3>
<h2>Paths</h2>
</body>

<body>
 <h1>Let's call it a draw(ing surface)</h1>
 <section>
  <h1>Diving in</h1>
 </section>
 <section>
  <h1>Simple shapes</h1>
 </section>
 <section>
  <h1>Canvas coordinates</h1>
  <section>
   <h1>Canvas coordinates diagram</h1>
  </section>
 </section>
 <section>
  <h1>Paths</h1>
 </section>
</body>

Authors might prefer the former style for its terseness, or the latter style for its convenience in the face of heavy editing; which is best is purely an issue of preferred authoring style.

The two styles can be combined, for compatibility with legacy tools while still future-proofing for when that compatibility is no longer needed. This third snippet again has the same outline as the previous two:

<body>
 <h1>Let's call it a draw(ing surface)</h1>
 <section>
  <h2>Diving in</h2>
 </section>
 <section>
  <h2>Simple shapes</h2>
 </section>
 <section>
  <h2>Canvas coordinates</h2>
  <section>
   <h3>Canvas coordinates diagram</h3>
  </section>
 </section>
 <section>
  <h2>Paths</h2>
 </section>
</body>

4.3.7 The `header` element

Categories:: Flow content.; Palpable content.
Contexts in which this element can be used:: Where flow content is expected.
Content model:: Flow content, but with no header, footer, or main element descendants.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: banner role (default - do not set) or presentation.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The header element represents introductory content for its nearest ancestor sectioning content or sectioning root element. A header typically contains a group of introductory or navigational aids. When the nearest ancestor sectioning content or sectioning root element is the body element, then it applies to the whole page.

The header element is not sectioning content; it doesn't introduce a new section.

In this example, the page has a page heading given by the h1 element, and two subsections whose headings are given by h2 elements. The content after the header element is still part of the last subsection started in the header element, because the header element doesn't take part in the outline algorithm.

<body>
 <header>
  <h1>Little Green Guys With Guns</h1>
  <nav>
   <ul>
    <li><a href="/games">Games</a>
    <li><a href="/forum">Forum</a>
    <li><a href="/download">Download</a>
   </ul>
  </nav>
  <h2>Important News</h2> <!-- this starts a second subsection -->
  <!-- this is part of the subsection entitled "Important News" -->
  <p>To play today's games you will need to update your client.</p>
  <h2>Games</h2> <!-- this starts a third subsection -->
 </header>
 <p>You have three active games:</p>
 <!-- this is still part of the subsection entitled "Games" -->
 ...

Categories:: Flow content.; Palpable content.
Contexts in which this element can be used:: Where flow content is expected.
Content model:: Flow content, but with no header, footer, or main element descendants.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: contentinfo role (default - do not set) or presentation.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The footer element represents a footer for its nearest ancestor sectioning content or sectioning root element. A footer typically contains information about its section such as who wrote it, links to related documents, copyright data, and the like.

When the footer element contains entire sections, they represent appendices, indexes, long colophons, verbose license agreements, and other such content.

Contact information for the author or editor of a section belongs in an address element, possibly itself inside a footer. Bylines and other information that could be suitable for both a header or a footer can be placed in either (or neither). The primary purpose of these elements is merely to help the author write self-explanatory markup that is easy to maintain and style; they are not intended to impose specific structures on authors.

Footers don't necessarily have to appear at the end of a section, though they usually do.

When the nearest ancestor sectioning content or sectioning root element is the body element, then it applies to the whole page.

The footer element is not sectioning content; it doesn't introduce a new section.

Here is an example which shows the footer element being used both for a site-wide footer and for a section footer.

<!DOCTYPE HTML>
<HTML><HEAD>
<TITLE>The Ramblings of a Scientist</TITLE>
<BODY>
<H1>The Ramblings of a Scientist</H1>
<ARTICLE>
 <H1>Episode 15</H1>
 <VIDEO SRC="/fm/015.ogv" CONTROLS PRELOAD>
  <P><A HREF="/fm/015.ogv">Download video</A>.</P>
 </VIDEO>
 <FOOTER> <!-- footer for article -->
  <P>Published <TIME DATETIME="2009-10-21T18:26-07:00">on 2009/10/21 at 6:26pm</TIME></P>
 </FOOTER>
</ARTICLE>
<ARTICLE>
 <H1>My Favorite Trains</H1>
 <P>I love my trains. My favorite train of all time is a Köf.</P>
 <P>It is fun to see them pull some coal cars because they look so
 dwarfed in comparison.</P>
 <FOOTER> <!-- footer for article -->
  <P>Published <TIME DATETIME="2009-09-15T14:54-07:00">on 2009/09/15 at 2:54pm</TIME></P>
 </FOOTER>
</ARTICLE>
<FOOTER> <!-- site wide footer -->
 <NAV>
  <P><A HREF="/credits.html">Credits</A> —
     <A HREF="/tos.html">Terms of Service</A> —
     <A HREF="/index.html">Blog Index</A></P>
 </NAV>
 <P>Copyright © 2009 Gordon Freeman</P>
</FOOTER>
</BODY>
</HTML>

Some site designs have what is sometimes referred to as "fat footers" — footers that contain a lot of material, including images, links to other articles, links to pages for sending feedback, special offers... in some ways, a whole "front page" in the footer.

This fragment shows the bottom of a page on a site with a "fat footer":

...
 <footer>
  <nav>
   <section>
    <h1>Articles</h1>
    <p><img src="images/somersaults.jpeg" alt=""> Go to the gym with
    our somersaults class! Our teacher Jim takes you through the paces
    in this two-part article. <a href="articles/somersaults/1">Part
    1</a> · <a href="articles/somersaults/2">Part 2</a></p>
    <p><img src="images/kindplus.jpeg"> Tired of walking on the edge of
    a clif<!-- sic -->? Our guest writer Lara shows you how to bumble
    your way through the bars. <a href="articles/kindplus/1">Read
    more...</a></p>
    <p><img src="images/crisps.jpeg"> The chips are down, now all
    that's left is a potato. What can you do with it? <a
    href="articles/crisps/1">Read more...</a></p>
   </section>
   <ul>
    <li> <a href="/about">About us...</a>
    <li> <a href="/feedback">Send feedback!</a>
    <li> <a href="/sitemap">Sitemap</a>
   </ul>
  </nav>
  <p><small>Copyright © 2015 The Snacker —
  <a href="/tos">Terms of Service</a></small></p>
 </footer>
</body>

4.3.9 The `address` element

Categories:: Flow content.; Palpable content.
Contexts in which this element can be used:: Where flow content is expected.
Content model:: Flow content, but with no heading content descendants, no sectioning content descendants, and no header, footer, or address element descendants.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: contentinfo role.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The address element represents the contact information for its nearest article or body element ancestor. If that is the body element, then the contact information applies to the document as a whole.

For example, a page at the W3C Web site related to HTML might include the following contact information:

<ADDRESS>
 <A href="../People/Raggett/">Dave Raggett</A>,
 <A href="../People/Arnaud/">Arnaud Le Hors</A>,
 contact persons for the <A href="Activity">W3C HTML Activity</A>
</ADDRESS>

The address element must not be used to represent arbitrary addresses (e.g. postal addresses), unless those addresses are in fact the relevant contact information. (The p element is the appropriate element for marking up postal addresses in general.)

The address element must not contain information other than contact information.

For example, the following is non-conforming use of the address element:

<ADDRESS>Last Modified: 1999/12/24 23:37:50</ADDRESS>

Typically, the address element would be included along with other information in a footer element.

The contact information for a node node is a collection of address elements defined by the first applicable entry from the following list:

If node is an article element
If node is a body element: The contact information consists of all the address elements that have node as an ancestor and do not have another body or article element ancestor that is a descendant of node.
If node has an ancestor element that is an article element
If node has an ancestor element that is a body element: The contact information of node is the same as the contact information of the nearest article or body element ancestor, whichever is nearest.
If node's node document has a body element: The contact information of node is the same as the contact information of the body element of the Document.
Otherwise: There is no contact information for node.

User agents may expose the contact information of a node to the user, or use it for other purposes, such as indexing sections based on the sections' contact information.

In this example the footer contains contact information and a copyright notice.

<footer>
 <address>
  For more details, contact
  <a href="mailto:js@example.com">John Smith</a>.
 </address>
 <p><small>© copyright 2038 Example Corp.</small></p>
</footer>

4.3.10 Headings and sections

The h1–h6 elements are headings.

The first element of heading content in an element of sectioning content represents the heading for that section. Subsequent headings of equal or higher rank start new (implied) sections, headings of lower rank start implied subsections that are part of the previous one. In both cases, the element represents the heading of the implied section.

Certain elements are said to be sectioning roots, including blockquote and td elements. These elements can have their own outlines, but the sections and headings inside these elements do not contribute to the outlines of their ancestors.

Sectioning content elements are always considered subsections of their nearest ancestor sectioning root or their nearest ancestor element of sectioning content, whichever is nearest, regardless of what implied sections other headings may have created.

For the following fragment:

<body>
 <h1>Foo</h1>
 <h2>Bar</h2>
 <blockquote>
  <h3>Bla</h3>
 </blockquote>
 <p>Baz</p>
 <h2>Quux</h2>
 <section>
  <h3>Thud</h3>
 </section>
 <p>Grunt</p>
</body>

...the structure would be:

Foo (heading of explicit body section, containing the "Grunt" paragraph)
1. Bar (heading starting implied section, containing a block quote and the "Baz" paragraph)
2. Quux (heading starting implied section with no content other than the heading itself)
3. Thud (heading of explicit section section)

Notice how the section ends the earlier implicit section so that a later paragraph ("Grunt") is back at the top level.

Sections may contain headings of any rank, but authors are strongly encouraged to either use only h1 elements, or to use elements of the appropriate rank for the section's nesting level.

Authors are also encouraged to explicitly wrap sections in elements of sectioning content, instead of relying on the implicit sections generated by having multiple headings in one element of sectioning content.

For example, the following is correct:

<body>
 <h4>Apples</h4>
 <p>Apples are fruit.</p>
 <section>
  <h2>Taste</h2>
  <p>They taste lovely.</p>
  <h6>Sweet</h6>
  <p>Red apples are sweeter than green ones.</p>
  <h1>Colour</h1>
  <p>Apples come in various colours.</p>
 </section>
</body>

However, the same document would be more clearly expressed as:

<body>
 <h1>Apples</h1>
 <p>Apples are fruit.</p>
 <section>
  <h2>Taste</h2>
  <p>They taste lovely.</p>
  <section>
   <h3>Sweet</h3>
   <p>Red apples are sweeter than green ones.</p>
  </section>
 </section>
 <section>
  <h2>Colour</h2>
  <p>Apples come in various colours.</p>
 </section>
</body>

Both of the documents above are semantically identical and would produce the same outline in compliant user agents.

This third example is also semantically identical, and might be easier to maintain (e.g. if sections are often moved around in editing):

<body>
 <h1>Apples</h1>
 <p>Apples are fruit.</p>
 <section>
  <h1>Taste</h1>
  <p>They taste lovely.</p>
  <section>
   <h1>Sweet</h1>
   <p>Red apples are sweeter than green ones.</p>
  </section>
 </section>
 <section>
  <h1>Colour</h1>
  <p>Apples come in various colours.</p>
 </section>
</body>

This final example would need explicit style rules to be rendered well in legacy browsers. Legacy browsers without CSS support would render all the headings as top-level headings.

There are currently no known implementations of the outline algorithm in graphical browsers or assistive technology user agents, although the algorithm is implemented in other software such as conformance checkers. Therefore the outline algorithm cannot be relied upon to convey document structure to users. Authors are advised to use heading rank (h1-h6) to convey document structure.

4.3.10.1 Creating an outline

This section defines an algorithm for creating an outline for a sectioning content element or a sectioning root element. It is defined in terms of a walk over the nodes of a DOM tree, in tree order, with each node being visited when it is entered and when it is exited during the walk.

The outline for a sectioning content element or a sectioning root element consists of a list of one or more potentially nested sections. The element for which an outline is created is said to be the outline's owner.

A section is a container that corresponds to some nodes in the original DOM tree. Each section can have one heading associated with it, and can contain any number of further nested sections. The algorithm for the outline also associates each node in the DOM tree with a particular section and potentially a heading. (The sections in the outline aren't section elements, though some may correspond to such elements — they are merely conceptual sections.)

The following markup fragment:

<body>
 <h1>A</h1>
 <p>B</p>
 <h2>C</h2>
 <p>D</p>
 <h2>E</h2>
 <p>F</p>
</body>

...results in the following outline being created for the body node (and thus the entire document):

Section created for body node.

Associated with heading "A".

Also associated with paragraph "B".

Nested sections:
1. Section implied for first h2 element.
  
  Associated with heading "C".
  
  Also associated with paragraph "D".
  
  No nested sections.
2. Section implied for second h2 element.
  
  Associated with heading "E".
  
  Also associated with paragraph "F".
  
  No nested sections.

The algorithm that must be followed during a walk of a DOM subtree rooted at a sectioning content element or a sectioning root element to determine that element's outline is as follows:

Let current outline target be null. (It holds the element whose outline is being created.)
Let current section be null. (It holds a pointer to a section, so that elements in the DOM can all be associated with a section.)
Create a stack to hold elements, which is used to handle nesting. Initialise this stack to empty.
Walk over the DOM in tree order, starting with the sectioning content element or sectioning root element at the root of the subtree for which an outline is to be created, and trigger the first relevant step below for each element as the walk enters and exits it.
When exiting an element, if that element is the element at the top of the stack

The element being exited is a heading content element or an element with a hidden attribute.

Pop that element from the stack.

If the top of the stack is a heading content element or an element with a hidden attribute
Do nothing.
When entering an element with a hidden attribute

Push the element being entered onto the stack. (This causes the algorithm to skip that element and any descendants of the element.)

When entering a sectioning content element
Run these steps:
1. If current outline target is not null, run these substeps:
  1. If the current section has no heading, create an implied heading and let that be the heading for the current section.
  2. Push current outline target onto the stack.
2. Let current outline target be the element that is being entered.
3. Let current section be a newly created section for the current outline target element.
4. Associate current outline target with current section.
5. Let there be a new outline for the new current outline target, initialised with just the new current section as the only section in the outline.
When exiting a sectioning content element, if the stack is not empty
Run these steps:
1. If the current section has no heading, create an implied heading and let that be the heading for the current section.
2. Pop the top element from the stack, and let the current outline target be that element.
3. Let current section be the last section in the outline of the current outline target element.
4. Append the outline of the sectioning content element being exited to the current section. (This does not change which section is the last section in the outline.)
When entering a sectioning root element
Run these steps:
1. If current outline target is not null, push current outline target onto the stack.
2. Let current outline target be the element that is being entered.
3. Let current outline target's parent section be current section.
4. Let current section be a newly created section for the current outline target element.
5. Let there be a new outline for the new current outline target, initialised with just the new current section as the only section in the outline.
When exiting a sectioning root element, if the stack is not empty
Run these steps:
1. If the current section has no heading, create an implied heading and let that be the heading for the current section.
2. Let current section be current outline target's parent section.
3. Pop the top element from the stack, and let the current outline target be that element.
When exiting a sectioning content element or a sectioning root element (when the stack is empty)

The current outline target is the element being exited, and it is the sectioning content element or a sectioning root element at the root of the subtree for which an outline is being generated.

If the current section has no heading, create an implied heading and let that be the heading for the current section.

Skip to the next step in the overall set of steps. (The walk is over.)

When entering a heading content element
If the current section has no heading, let the element being entered be the heading for the current section.

Otherwise, if the element being entered has a rank equal to or higher than the heading of the last section of the outline of the current outline target, or if the heading of the last section of the outline of the current outline target is an implied heading, then create a new section and append it to the outline of the current outline target element, so that this new section is the new last section of that outline. Let current section be that new section. Let the element being entered be the new heading for the current section.

Otherwise, run these substeps:
1. Let candidate section be current section.
2. Heading loop: If the element being entered has a rank lower than the rank of the heading of the candidate section, then create a new section, and append it to candidate section. (This does not change which section is the last section in the outline.) Let current section be this new section. Let the element being entered be the new heading for the current section. Abort these substeps.
3. Let new candidate section be the section that contains candidate section in the outline of current outline target.
4. Let candidate section be new candidate section.
5. Return to the step labeled heading loop.
Push the element being entered onto the stack. (This causes the algorithm to skip any descendants of the element.)

Recall that h1 has the highest rank, and h6 has the lowest rank.
Otherwise
Do nothing.
In addition, whenever the walk exits a node, after doing the steps above, if the node is not associated with a section yet, associate the node with the section current section.
Associate all non-element nodes that are in the subtree for which an outline is being created with the section with which their parent element is associated.
Associate all nodes in the subtree with the heading of the section with which they are associated, if any.

The tree of sections created by the algorithm above, or a proper subset thereof, must be used when generating document outlines, for example when generating tables of contents.

The outline created for the body element of a Document is the outline of the entire document.

When creating an interactive table of contents, entries should jump the user to the relevant sectioning content element, if the section was created for a real element in the original document, or to the relevant heading content element, if the section in the tree was generated for a heading in the above process.

Selecting the first section of the document therefore always takes the user to the top of the document, regardless of where the first heading in the body is to be found.

The outline depth of a heading content element associated with a section section is the number of sections that are ancestors of section in the outermost outline that section finds itself in when the outlines of its Document's elements are created, plus 1. The outline depth of a heading content element not associated with a section is 1.

User agents should provide default headings for sections that do not have explicit section headings.

Consider the following snippet:

<body>
 <nav>
  <p><a href="/">Home</a></p>
 </nav>
 <p>Hello world.</p>
 <aside>
  <p>My cat is cute.</p>
 </aside>
</body>

Although it contains no headings, this snippet has three sections: a document (the body) with two subsections (a nav and an aside). A user agent could present the outline as follows:

Untitled document
1. Navigation
2. Sidebar

These default headings ("Untitled document", "Navigation", "Sidebar") are not specified by this specification, and might vary with the user's language, the page's language, the user's preferences, the user agent implementor's preferences, etc.

The following JavaScript function shows how the tree walk could be implemented. The root argument is the root of the tree to walk (either a sectioning content element or a sectioning root element), and the enter and exit arguments are callbacks that are called with the nodes as they are entered and exited. [ECMA262]

function (root, enter, exit) {
  var node = root;
  start: while (node) {
    enter(node);
    if (node.firstChild) {
      node = node.firstChild;
      continue start;
    }
    while (node) {
      exit(node);
      if (node == root) {
        node = null;
      } else if (node.nextSibling) {
        node = node.nextSibling;
        continue start;
      } else {
        node = node.parentNode;
      }
    }
  }
}

4.3.10.2 Sample outlines

This section is non-normative.

The following document shows a straight-forward application of the outline algorithm. First, here is the document, which is a book with very short chapters and subsections:

<!DOCTYPE HTML>
<title>The Tax Book (all in one page)</title>
<h1>The Tax Book</h1>
<h2>Earning money</h2>
<p>Earning money is good.</p>
<h3>Getting a job</h3>
<p>To earn money you typically need a job.</p>
<h2>Spending money</h2>
<p>Spending is what money is mainly used for.</p>
<h3>Cheap things</h3>
<p>Buying cheap things often not cost-effective.</p>
<h3>Expensive things</h3>
<p>The most expensive thing is often not the most cost-effective either.</p>
<h2>Investing money</h2>
<p>You can lend your money to other people.</p>
<h2>Losing money</h2>
<p>If you spend money or invest money, sooner or later you will lose money.
<h3>Poor judgement</h3>
<p>Usually if you lose money it's because you made a mistake.</p>

This book would form the following outline:

The Tax Book
1. Earning money
  1. Getting a job
2. Spending money
  1. Cheap things
  2. Expensive things
3. Investing money
4. Losing money
  1. Poor judgement

Notice that the title element does not participate in the outline.

Here is a similar document, but this time using section elements to get the same effect:

<!DOCTYPE HTML>
<title>The Tax Book (all in one page)</title>
<h1>The Tax Book</h1>
<section>
 <h1>Earning money</h1>
 <p>Earning money is good.</p>
 <section>
  <h1>Getting a job</h1>
  <p>To earn money you typically need a job.</p>
 </section>
</section>
<section>
 <h1>Spending money</h1>
 <p>Spending is what money is mainly used for.</p>
 <section>
  <h1>Cheap things</h1>
  <p>Buying cheap things often not cost-effective.</p>
 </section>
 <section>
  <h1>Expensive things</h1>
  <p>The most expensive thing is often not the most cost-effective either.</p>
 </section>
</section>
<section>
 <h1>Investing money</h1>
 <p>You can lend your money to other people.</p>
</section>
<section>
 <h1>Losing money</h1>
 <p>If you spend money or invest money, sooner or later you will lose money.
 <section>
  <h1>Poor judgement</h1>
  <p>Usually if you lose money it's because you made a mistake.</p>
 </section>
</section>

This book would form the same outline:

The Tax Book
1. Earning money
  1. Getting a job
2. Spending money
  1. Cheap things
  2. Expensive things
3. Investing money
4. Losing money
  1. Poor judgement

A document can contain multiple top-level headings:

<!DOCTYPE HTML>
<title>Alphabetic Fruit</title>
<h1>Apples</h1>
<p>Pomaceous.</p>
<h1>Bananas</h1>
<p>Edible.</p>
<h1>Carambola</h1>
<p>Star.</p>

This would form the following simple outline consisting of three top-level sections:

Apples
Bananas
Carambola

Effectively, the body element is split into three.

Mixing both the h1–h6 model and the section/h1 model can lead to some unintuitive results.

Consider for example the following, which is just the previous example but with the contents of the (implied) body wrapped in a section:

<!DOCTYPE HTML>
<title>Alphabetic Fruit</title>
<section>
 <h1>Apples</h1>
 <p>Pomaceous.</p>
 <h1>Bananas</h1>
 <p>Edible.</p>
 <h1>Carambola</h1>
 <p>Star.</p>
</section>

The resulting outline would be:

(untitled page)
1. Apples
2. Bananas
3. Carambola

This result is described as unintuitive because it results in three subsections even though there's only one section element. Effectively, the section is split into three, just like the implied body element in the previous example.

(In this example, "(untitled page)" is the implied heading for the body element, since it has no explicit heading.)

Headings never rise above other sections. Thus, in the following example, the first h1 does not actually describe the page header; it describes the header for the second half of the page:

<!DOCTYPE HTML>
<title>Feathers on The Site of Encyclopedic Knowledge</title>
<section>
 <h1>A plea from our caretakers</h1>
 <p>Please, we beg of you, send help! We're stuck in the server room!</p>
</section>
<h1>Feathers</h1>
<p>Epidermal growths.</p>

The resulting outline would be:

(untitled page)
1. A plea from our caretakers
Feathers

Thus, when an article element starts with a nav block and only later has its heading, the result is that the nav block is not part of the same section as the rest of the article in the outline. For instance, take this document:

<!DOCTYPE HTML>
<title>We're adopting a child! — Ray's blog</title>
<h1>Ray's blog</h1>
<article>
 <header>
  <nav>
   <a href="?t=-1d">Yesterday</a>;
   <a href="?t=-7d">Last week</a>;
   <a href="?t=-1m">Last month</a>
  </nav>
  <h1>We're adopting a child!</h1>
 </header>
 <main>
  <p>As of today, Janine and I have signed the papers to become
  the proud parents of baby Diane! We've been looking forward to
  this day for weeks.</p>
 </main>
</article>

The resulting outline would be:

Ray's blog
1. Untitled article
  1. Untitled navigation section
2. We're adopting a child!

Also worthy of note in this example is that the header and main elements have no effect whatsoever on the document outline.

4.3.10.3 Exposing outlines to users

User agents are encouraged to expose page outlines to users to aid in navigation. This is especially true for non-visual media, e.g. screen readers.

However, to mitigate the difficulties that arise from authors misusing sectioning content, user agents are also encouraged to offer a mode that navigates the page using heading content alone.

For instance, a user agent could map the arrow keys as follows:

Shift+← Left: Go to previous section, including subsectons of previous sections
Shift+→ Right: Go to next section, including subsections of the current section
Shift+↑ Up: Go to parent section of the current section
Shift+↓ Down: Go to next section, skipping subsections of the current section

Plus in addition, the user agent could map the j and k keys to navigating to the previous or next element of heading content, regardless of the section's outline depth and ignoring sections with no headings.

4.3.11 Usage summary

This section is non-normative.

Element	Purpose
Element	Example
`body`	The main content of the document.
`body`	<!DOCTYPE HTML> <html> <head> <title>Steve Hill's Home Page</title> </head> <body> <p>Hard Trance is My Life.</p> </body> </html>
`article`	A complete, or self-contained, composition in a document, page, application, or site and that is, in principle, independently distributable or reusable, e.g. in syndication. This could be a forum post, a magazine or newspaper article, a blog entry, a user-submitted comment, an interactive widget or gadget, or any other independent item of content.
`article`	<article> <img src="/tumblr_masqy2s5yn1rzfqbpo1_500.jpg" alt="Yellow smiley face with the caption 'masif'"> <p>My fave Masif tee so far!</p> <footer>Posted 2 days ago</footer> </article> <article> <img src="/tumblr_m9tf6wSr6W1rzfqbpo1_500.jpg" alt=""> <p>Happy 2nd birthday Masif Saturdays!!!</p> <footer>Posted 3 weeks ago</footer> </article>
`section`	A generic section of a document or application. A section, in this context, is a thematic grouping of content, typically with a heading.
`section`	<h1>Biography</h1> <section> <h1>The facts</h1> <p>1500+ shows, 14+ countries</p> </section> <section> <h1>2010/2011 figures per year</h1> <p>100+ shows, 8+ countries</p> </section>
`nav`	A section of a page that links to other pages or to parts within the page: a section with navigation links.
`nav`	<nav> <p><a href="/">Home</a> <p><a href="/biog.html">Bio</a> <p><a href="/discog.html">Discog</a> </nav>
`aside`	A section of a page that consists of content that is tangentially related to the content around the `aside` element, and which could be considered separate from that content. Such sections are often represented as sidebars in printed typography.
`aside`	<h1>Music</h1> <p>As any burner can tell you, the event has a lot of trance.</p> <aside>You can buy the music we played at our <a href="buy.html">playlist page</a>.</aside> <p>This year we played a kind of trance that originated in Belgium, Germany, and the Netherlands in the mid 90s.</p>
`h1`–`h6`	A section heading
`h1`–`h6`	<h1>The Guide To Music On The Playa</h1> <h2>The Main Stage</h2> <p>If you want to play on a stage, you should bring one.</p> <h2>Amplified Music</h2> <p>Amplifiers up to 300W or 90dB are welcome.</p>
`header`	A group of introductory or navigational aids.
`header`	<article> <header> <h1>Hard Trance is My Life</h1> <p>By DJ Steve Hill and Technikal</p> </header> <p>The album with the amusing punctuation has red artwork.</p> </article>
`footer`	A footer for its nearest ancestor sectioning content or sectioning root element. A footer typically contains information about its section such as who wrote it, links to related documents, copyright data, and the like.
`footer`	<article> <h1>Hard Trance is My Life</h1> <p>The album with the amusing punctuation has red artwork.</p> <footer> <p>Artists: DJ Steve Hill and Technikal</p> </footer> </article>

4.3.11.1 Article or section?

This section is non-normative.

A section forms part of something else. An article is its own thing. But how does one know which is which? Mostly the real answer is "it depends on author intent".

For example, one could imagine a book with a "Granny Smith" chapter that just said "These juicy, green apples make a great filling for apple pies."; that would be a section because there'd be lots of other chapters on (maybe) other kinds of apples.

On the other hand, one could imagine a tweet or reddit comment or tumblr post or newspaper classified ad that just said "Granny Smith. These juicy, green apples make a great filling for apple pies."; it would then be articles because that was the whole thing.

A comment on an article is not part of the article on which it is commenting, therefore it is its own article.

4.4 Grouping content

4.4.1 The `p` element

Where flow content is expected.

A p element's end tag can be omitted if the p element is immediately followed by an address, article, aside, blockquote, details, div, dl, fieldset, figcaption, figure, , form, h1, h2, h3, h4, h5, h6, header, hgroup, hr, main, , nav, ol, p, pre, section, table, or ul element, or if there is no more content in the parent element and the parent element is an HTML element that is not an a, audio, del, ins, map, noscript, or video element.

Allowed ARIA role attribute values:

Any aria-* attributes applicable to the allowed roles.

interface HTMLParagraphElement : HTMLElement {
  // also has obsolete members
};

The p element represents a paragraph.

While paragraphs are usually represented in visual media by blocks of text that are physically separated from adjacent blocks through blank lines, a style sheet or user agent would be equally justified in presenting paragraph breaks in a different manner, for instance using inline pilcrows (¶).

The following examples are conforming HTML fragments:

<p>The little kitten gently seated himself on a piece of
carpet. Later in his life, this would be referred to as the time the
cat sat on the mat.</p>

<fieldset>
 <legend>Personal information</legend>
 <p>
   <label>Name: <input name="n"></label>
   <label><input name="anon" type="checkbox"> Hide from other users</label>
 </p>
 <p><label>Address: <textarea name="a"></textarea></label></p>
</fieldset>

<p>There was once an example from Femley,<br>
Whose markup was of dubious quality.<br>
The validator complained,<br>
So the author was pained,<br>
To move the error from the markup to the rhyming.</p>

The p element should not be used when a more specific element is more appropriate.

The following example is technically correct:

<section>
 <!-- ... -->
 <p>Last modified: 2001-04-23</p>
 <p>Author: fred@example.com</p>
</section>

However, it would be better marked-up as:

<section>
 <!-- ... -->
 <footer>Last modified: 2001-04-23</footer>
 <address>Author: fred@example.com</address>
</section>

Or:

<section>
 <!-- ... -->
 <footer>
  <p>Last modified: 2001-04-23</p>
  <address>Author: fred@example.com</address>
 </footer>
</section>

List elements (in particular, ol and ul elements) cannot be children of p elements. When a sentence contains a bulleted list, therefore, one might wonder how it should be marked up.

For instance, this fantastic sentence has bullets relating to

wizards,
faster-than-light travel, and
telepathy,

and is further discussed below.

The solution is to realise that a paragraph, in HTML terms, is not a logical concept, but a structural one. In the fantastic example above, there are actually five paragraphs as defined by this specification: one before the list, one for each bullet, and one after the list.

The markup for the above example could therefore be:

<p>For instance, this fantastic sentence has bullets relating to</p>
<ul>
 <li>wizards,
 <li>faster-than-light travel, and
 <li>telepathy,
</ul>
<p>and is further discussed below.</p>

Authors wishing to conveniently style such "logical" paragraphs consisting of multiple "structural" paragraphs can use the div element instead of the p element.

Thus for instance the above example could become the following:

<div>For instance, this fantastic sentence has bullets relating to
<ul>
 <li>wizards,
 <li>faster-than-light travel, and
 <li>telepathy,
</ul>
and is further discussed below.</div>

This example still has five structural paragraphs, but now the author can style just the div instead of having to consider each part of the example separately.

4.4.2 The `hr` element

Where flow content is expected.

No end tag.

Allowed ARIA role attribute values:

separator (default - do not set) or presentation.

Any aria-* attributes applicable to the allowed roles.

interface HTMLHRElement : HTMLElement {
  // also has obsolete members
};

The hr element represents a paragraph-level thematic break, e.g. a scene change in a story, or a transition to another topic within a section of a reference book.

The following fictional extract from a project manual shows two sections that use the hr element to separate topics within the section.

<section>
 <h1>Communication</h1>
 <p>There are various methods of communication. This section
 covers a few of the important ones used by the project.</p>
 <hr>
 <p>Communication stones seem to come in pairs and have mysterious
 properties:</p>
 <ul>
  <li>They can transfer thoughts in two directions once activated
  if used alone.</li>
  <li>If used with another device, they can transfer one's
  consciousness to another body.</li>
  <li>If both stones are used with another device, the
  consciousnesses switch bodies.</li>
 </ul>
 <hr>
 <p>Radios use the electromagnetic spectrum in the meter range and
 longer.</p>
 <hr>
 <p>Signal flares use the electromagnetic spectrum in the
 nanometer range.</p>
</section>
<section>
 <h1>Food</h1>
 <p>All food at the project is rationed:</p>
 <dl>
  <dt>Potatoes</dt>
  <dd>Two per day</dd>
  <dt>Soup</dt>
  <dd>One bowl per day</dd>
 </dl>
 <hr>
 <p>Cooking is done by the chefs on a set rotation.</p>
</section>

There is no need for an hr element between the sections themselves, since the section elements and the h1 elements imply thematic changes themselves.

The following extract from Pandora's Star by Peter F. Hamilton shows two paragraphs that precede a scene change and the paragraph that follows it. The scene change, represented in the printed book by a gap containing a solitary centered star between the second and third paragraphs, is here represented using the hr element.

<p>Dudley was ninety-two, in his second life, and fast approaching
time for another rejuvenation. Despite his body having the physical
age of a standard fifty-year-old, the prospect of a long degrading
campaign within academia was one he regarded with dread. For a
supposedly advanced civilization, the Intersolar Commonwealth could be
appallingly backward at times, not to mention cruel.</p>
<p><i>Maybe it won't be that bad</i>, he told himself. The lie was
comforting enough to get him through the rest of the night's
shift.</p>
<hr>
<p>The Carlton AllLander drove Dudley home just after dawn. Like the
astronomer, the vehicle was old and worn, but perfectly capable of
doing its job. It had a cheap diesel engine, common enough on a
semi-frontier world like Gralmond, although its drive array was a
thoroughly modern photoneural processor. With its high suspension and
deep-tread tyres it could plough along the dirt track to the
observatory in all weather and seasons, including the metre-deep snow
of Gralmond's winters.</p>

The hr element does not affect the document's outline.

4.4.3 The `pre` element

Where flow content is expected.

Neither tag is omissible.

Allowed ARIA role attribute values:

Any aria-* attributes applicable to the allowed roles.

interface HTMLPreElement : HTMLElement {
  // also has obsolete members
};

The pre element represents a block of preformatted text, in which structure is represented by typographic conventions rather than by elements.

In the HTML syntax, a leading newline character immediately following the pre element start tag is stripped.

Some examples of cases where the pre element could be used:

Including an e-mail, with paragraphs indicated by blank lines, lists indicated by lines prefixed with a bullet, and so on.
Including fragments of computer code, with structure indicated according to the conventions of that language.
Displaying ASCII art.

Authors are encouraged to consider how preformatted text will be experienced when the formatting is lost, as will be the case for users of speech synthesizers, braille displays, and the like. For cases like ASCII art, it is likely that an alternative presentation, such as a textual description, would be more universally accessible to the readers of the document.

To represent a block of computer code, the pre element can be used with a code element; to represent a block of computer output the pre element can be used with a samp element. Similarly, the kbd element can be used within a pre element to indicate text that the user is to enter.

This element has rendering requirements involving the bidirectional algorithm.

In the following snippet, a sample of computer code is presented.

<p>This is the <code>Panel</code> constructor:</p>
<pre><code>function Panel(element, canClose, closeHandler) {
  this.element = element;
  this.canClose = canClose;
  this.closeHandler = function () { if (closeHandler) closeHandler() };
}</code></pre>

In the following snippet, samp and kbd elements are mixed in the contents of a pre element to show a session of Zork I.

<pre><samp>You are in an open field west of a big white house with a boarded
front door.
There is a small mailbox here.

></samp> <kbd>open mailbox</kbd>

<samp>Opening the mailbox reveals:
A leaflet.

></samp></pre>

The following shows a contemporary poem that uses the pre element to preserve its unusual formatting, which forms an intrinsic part of the poem itself.

<pre>                maxling

it is with a          heart
               heavy

that i admit loss of a feline
        so           loved

a friend lost to the
        unknown
                                (night)

~cdr 11dec07</pre>

4.4.4 The `blockquote` element

Where flow content is expected.

cite - Link to the source of the quotation.

Neither tag is omissible

Allowed ARIA role attribute values:

Any aria-* attributes applicable to the allowed roles.

interface HTMLQuoteElement : HTMLElement {
           attribute DOMString cite;
};

The HTMLQuoteElement interface is also used by the q element.

The blockquote element represents content that is quoted from another source, optionally with a citation which must be within a footer or cite element, and optionally with in-line changes such as annotations and abbreviations.

Content inside a blockquote other than citations and in-line changes must be quoted from another source, whose address, if it has one, may be cited in the cite attribute.

In cases where a page contains contributions from multiple people, such as comments on a blog post, 'another source' can include text from the same page, written by another person.

If the cite attribute is present, it must be a valid URL potentially surrounded by spaces. To obtain the corresponding citation link, the value of the attribute must be resolved relative to the element. User agents may allow users to follow such citation links, but they are primarily intended for private use (e.g. by server-side scripts collecting statistics about a site's use of quotations), not for readers.

The cite IDL attribute must reflect the element's cite content attribute.

The content of a blockquote may be abbreviated, may have context added or may have annotations. Any such additions or changes to quoted text must be indicated in the text (at the text level). This may mean the use of notational conventions or explicit remarks, such as "emphasis mine".

For example, in English, abbreviations are traditionally identified using square brackets. Consider a page with the sentence "Fred ate the cracker. He then said he liked apples and fish."; it could be quoted as follows:

<blockquote>
 <p>[Fred] then said he liked [...] fish.</p>
</blockquote>

Quotation marks may be used to delineate between quoted text and annotations within a blockquote.

For example, an in-line note provided by the author:

 <figure>
 <blockquote>
 "That monster custom, who all sense doth eat
 Of habit's devil," <abbr title="et cetera">&c.</abbr> not in Folio
 
 "What a falling off was there !
 From me, whose love was of that dignity
 That it went hand in hand even with the vow
 I made to her in marriage, and to decline
 Upon a wretch."
 </blockquote>
 <footer>
 — <cite class="title">Shakespeare manual</cite> by <cite class="author">Frederick Gard Fleay</cite>, 
 p19 (in Google Books)
 </footer>
 </figure>

In the example above, the citation is contained within the footer of a figure element, this groups and associates the information, about the quote, with the quote. The figcaption element was not used, in this case, as a container for the citation as it is not a caption.

Attribution for the quotation, may be be placed inside the blockquote element, but must be within a cite element for in-text attributions or within a footer element.

For example, here the attribution is given in a footer after the quoted text, to clearly relate the quote to its attribution:

<blockquote>
 <p>I contend that we are both atheists. I just believe in one fewer
 god than you do. When you understand why you dismiss all the other
 possible gods, you will understand why I dismiss yours.</p>
 <footer>— <cite>Stephen Roberts</cite></footer>
 </blockquote>

Here the attribution is given in a cite element on the last line of the quoted text. Note that a link to the author is also included.

<blockquote>
 The people recognize themselves in their commodities; they find their 
 soul in their automobile, hi-fi set, split-level home, kitchen equipment. 
 — <cite><a href="http://en.wikipedia.org/wiki/Herbert_Marcuse">Herbert Marcuse</a></cite>
 </blockquote>

Here the attribution is given in a footer after the quoted text, and metadata about the reference has been added using the Microdata syntax (note it could have equally been marked up using RDFA Lite).

<blockquote>
 <p>... she said she would not sign any deposition containing the word "amorous" 
 instead of "advances". For her the difference was of crucial significance, 
 and one of the reasons she had separated from her husband was that he had never been 
 amorous but had consistently made advances.</p>
 
 <footer itemscope itemtype="http://schema.org/Book">
  <span itemprop="author">Heinrich Böll</span>,
  <span itemprop="name">The Lost Honor of Katharina Blum</span>, 
  <span itemprop="datePublished">January 1, 1974</span>
 </footer>
 </blockquote>

There is no formal method for indicating the markup in a blockquote is from a quoted source. It is suggested that if the footer or cite elements are included and these elements are also being used within a blockquote to identify citations, the elements from the quoted source could be annotated with metadata to identify their origin, for example by using the class attribute (a defined extensibility mechanism).

In this example the source of a quote includes a cite element, which is annotated using the class attribute:

  <blockquote>
  <p>My favorite book is <cite class="from-source">At Swim-Two-Birds</cite></p>
  <footer>- <cite>Mike[tm]Smith</cite></footer>
  </blockquote>

The other examples below show other ways of showing attribution.

Here a blockquote element is used in conjunction with a figure element and its figcaption:

<figure>
 <blockquote>
  <p>The truth may be puzzling. It may take some work to grapple with.
  It may be counterintuitive. It may contradict deeply held
  prejudices. It may not be consonant with what we desperately want to
  be true. But our preferences do not determine what's true. We have a
  method, and that method helps us to reach not absolute truth, only
  asymptotic approaches to the truth — never there, just closer
  and closer, always finding vast new oceans of undiscovered
  possibilities. Cleverly designed experiments are the key.</p>
 </blockquote>
 <figcaption><cite>Carl Sagan</cite>, in "<cite>Wonder and Skepticism</cite>", from
 the <cite>Skeptical Enquirer</cite> Volume 19, Issue 1 (January-February
 1995)</figcaption>
</figure>

This next example shows the use of cite alongside blockquote:

<p>His next piece was the aptly named <cite>Sonnet 130</cite>:</p>
<blockquote cite="http://quotes.example.org/s/sonnet130.html">
  <p>My mistress' eyes are nothing like the sun,<br>
  Coral is far more red, than her lips red,<br>
  ...

This example shows how a forum post could use blockquote to show what post a user is replying to. The article element is used for each post, to mark up the threading.

<article>
 <h1><a href="http://bacon.example.com/?blog=109431">Bacon on a crowbar</a></h1>
 <article>
  <header><strong>t3yw</strong> 12 points 1 hour ago</header>
  <p>I bet a narwhal would love that.</p>
  <footer><a href="?pid=29578">permalink</a></footer>
  <article>
   <header><strong>greg</strong> 8 points 1 hour ago</header>
   <blockquote><p>I bet a narwhal would love that.</p></blockquote>
   <p>Dude narwhals don't eat bacon.</p>
   <footer><a href="?pid=29579">permalink</a></footer>
   <article>
    <header><strong>t3yw</strong> 15 points 1 hour ago</header>
    <blockquote>
     <blockquote><p>I bet a narwhal would love that.</p></blockquote>
     <p>Dude narwhals don't eat bacon.</p>
    </blockquote>
    <p>Next thing you'll be saying they don't get capes and wizard
    hats either!</p>
    <footer><a href="?pid=29580">permalink</a></footer>
    <article>
     <article>
      <header><strong>boing</strong> -5 points 1 hour ago</header>
      <p>narwhals are worse than ceiling cat</p>
      <footer><a href="?pid=29581">permalink</a></footer>
     </article>
    </article>
   </article>
  </article>
  <article>
   <header><strong>fred</strong> 1 points 23 minutes ago</header>
   <blockquote><p>I bet a narwhal would love that.</p></blockquote>
   <p>I bet they'd love to peel a banana too.</p>
   <footer><a href="?pid=29582">permalink</a></footer>
  </article>
 </article>
</article>

This example shows the use of a blockquote for short snippets, demonstrating that one does not have to use p elements inside blockquote elements:

<p>He began his list of "lessons" with the following:</p>
<blockquote>One should never assume that his side of
the issue will be recognized, let alone that it will
be conceded to have merits.</blockquote>
<p>He continued with a number of similar points, ending with:</p>
<blockquote>Finally, one should be prepared for the threat
of breakdown in negotiations at any given moment and not
be cowed by the possibility.</blockquote>
<p>We shall now discuss these points...

Examples of how to represent a conversation are shown in a later section; it is not appropriate to use the cite and blockquote elements for this purpose.

4.4.5 The `ol` element

If the element's children include at least one li element: Palpable content.

Where flow content is expected.

Zero or more li and script-supporting elements.

Neither tag is omissible.

reversed — Number the list backwards

start — Ordinal value of the first item

type — Kind of list marker

Allowed ARIA role attribute values:

list role (default - do not set), directory, group, listbox, menu, menubar, presentation, radiogroup, tablist, toolbar or tree.

Any aria-* attributes applicable to the allowed roles.

interface HTMLOListElement : HTMLElement {
  attribute boolean reversed;
  attribute long start;
  attribute DOMString type;

  // also has obsolete members
};

The ol element represents a list of items, where the items have been intentionally ordered, such that changing the order would change the meaning of the document.

The items of the list are the li element child nodes of the ol element, in tree order.

The reversed attribute is a boolean attribute. If present, it indicates that the list is a descending list (..., 3, 2, 1). If the attribute is omitted, the list is an ascending list (1, 2, 3, ...).

The start attribute, if present, must be a valid integer giving the ordinal value of the first list item.

If the start attribute is present, user agents must parse it as an integer, in order to determine the attribute's value. The default value, used if the attribute is missing or if the value cannot be converted to a number according to the referenced algorithm, is 1 if the element has no reversed attribute, and is the number of child li elements otherwise.

The first item in the list has the ordinal value given by the ol element's start attribute, unless that li element has a value attribute with a value that can be successfully parsed, in which case it has the ordinal value given by that value attribute.

Each subsequent item in the list has the ordinal value given by its value attribute, if it has one, or, if it doesn't, the ordinal value of the previous item, plus one if the reversed is absent, or minus one if it is present.

The type attribute can be used to specify the kind of marker to use in the list, in the cases where that matters (e.g. because items are to be referenced by their number/letter). The attribute, if specified, must have a value that is a case-sensitive match for one of the characters given in the first cell of one of the rows of the following table. The type attribute represents the state given in the cell in the second column of the row whose first cell matches the attribute's value; if none of the cells match, or if the attribute is omitted, then the attribute represents the decimal state.

Keyword	State	Description	Examples for values 1-3 and 3999-4001
`1` (U+0031)	decimal	Decimal numbers	`1.`	`2.`	`3.`	...	`3999.`	`4000.`	`4001.`	...
`a` (U+0061)	lower-alpha	Lowercase latin alphabet	`a.`	`b.`	`c.`	...	`ewu.`	`ewv.`	`eww.`	...
`A` (U+0041)	upper-alpha	Uppercase latin alphabet	`A.`	`B.`	`C.`	...	`EWU.`	`EWV.`	`EWW.`	...
`i` (U+0069)	lower-roman	Lowercase roman numerals	`i.`	`ii.`	`iii.`	...	`mmmcmxcix.`	`i̅v̅.`	`i̅v̅i.`	...
`I` (U+0049)	upper-roman	Uppercase roman numerals	`I.`	`II.`	`III.`	...	`MMMCMXCIX.`	`I̅V̅.`	`I̅V̅I.`	...

User agents should render the items of the list in a manner consistent with the state of the type attribute of the ol element. Numbers less than or equal to zero should always use the decimal system regardless of the type attribute.

For CSS user agents, a mapping for this attribute to the 'list-style-type' CSS property is given in the rendering section (the mapping is straightforward: the states above have the same names as their corresponding CSS values).

It is possible to redefine the default CSS list styles used to implement this attribute in CSS user agents; doing so will affect how list items are rendered.

The reversed, start, and type IDL attributes must reflect the respective content attributes of the same name. The start IDL attribute has the same default as its content attribute.

The following markup shows a list where the order matters, and where the ol element is therefore appropriate. Compare this list to the equivalent list in the ul section to see an example of the same items using the ul element.

<p>I have lived in the following countries (given in the order of when
I first lived there):</p>
<ol>
 <li>Switzerland
 <li>United Kingdom
 <li>United States
 <li>Norway
</ol>

Note how changing the order of the list changes the meaning of the document. In the following example, changing the relative order of the first two items has changed the birthplace of the author:

<p>I have lived in the following countries (given in the order of when
I first lived there):</p>
<ol>
 <li>United Kingdom
 <li>Switzerland
 <li>United States
 <li>Norway
</ol>

4.4.6 The `ul` element

If the element's children include at least one li element: Palpable content.

Where flow content is expected.

Zero or more li and script-supporting elements.

Neither tag is omissible.

Allowed ARIA role attribute values:

list role (default - do not set), directory, group, listbox, menu, menubar, presentation,radiogroup, tablist, toolbar or tree.

Any aria-* attributes applicable to the allowed roles.

interface HTMLUListElement : HTMLElement {
  // also has obsolete members
};

The ul element represents a list of items, where the order of the items is not important — that is, where changing the order would not materially change the meaning of the document.

The items of the list are the li element child nodes of the ul element.

The following markup shows a list where the order does not matter, and where the ul element is therefore appropriate. Compare this list to the equivalent list in the ol section to see an example of the same items using the ol element.

<p>I have lived in the following countries:</p>
<ul>
 <li>Norway
 <li>Switzerland
 <li>United Kingdom
 <li>United States
</ul>

Note that changing the order of the list does not change the meaning of the document. The items in the snippet above are given in alphabetical order, but in the snippet below they are given in order of the size of their current account balance in 2007, without changing the meaning of the document whatsoever:

<p>I have lived in the following countries:</p>
<ul>
 <li>Switzerland
 <li>Norway
 <li>United Kingdom
 <li>United States
</ul>

4.4.7 The `li` element

None.

Inside ol elements.

Inside ul elements.

Inside elements whose attribute is in the state.

An li element's end tag can be omitted if the li element is immediately followed by another li element or if there is no more content in the parent element.

If the element is a child of an ol element: value — Ordinal value of the list item

Allowed ARIA role attribute values:

listitem role (default - do not set), menuitem, menuitemcheckbox, menuitemradio, option, radio, tab, treeitem or presentation.

Any aria-* attributes applicable to the allowed roles.

interface HTMLLIElement : HTMLElement {
  attribute long value;

  // also has obsolete members
};

The li element represents a list item. If its parent element is an ol, ul, or menu element, then the element is an item of the parent element's list, as defined for those elements. Otherwise, the list item has no defined list-related relationship to any other li element.

If the parent element is an ol element, then the li element has an ordinal value.

The value attribute, if present, must be a valid integer giving the ordinal value of the list item.

If the value attribute is present, user agents must parse it as an integer, in order to determine the attribute's value. If the attribute's value cannot be converted to a number, the attribute must be treated as if it was absent. The attribute has no default value.

The value attribute is processed relative to the element's parent ol element (q.v.), if there is one. If there is not, the attribute has no effect.

The value IDL attribute must reflect the value of the value content attribute.

The following example, the top ten movies are listed (in reverse order). Note the way the list is given a title by using a figure element and its figcaption element.

<figure>
 <figcaption>The top 10 movies of all time</figcaption>
 <ol>
  <li value="10"><cite>Josie and the Pussycats</cite>, 2001</li>
  <li value="9"><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li>
  <li value="8"><cite>A Bug's Life</cite>, 1998</li>
  <li value="7"><cite>Toy Story</cite>, 1995</li>
  <li value="6"><cite>Monsters, Inc</cite>, 2001</li>
  <li value="5"><cite>Cars</cite>, 2006</li>
  <li value="4"><cite>Toy Story 2</cite>, 1999</li>
  <li value="3"><cite>Finding Nemo</cite>, 2003</li>
  <li value="2"><cite>The Incredibles</cite>, 2004</li>
  <li value="1"><cite>Ratatouille</cite>, 2007</li>
 </ol>
</figure>

The markup could also be written as follows, using the reversed attribute on the ol element:

<figure>
 <figcaption>The top 10 movies of all time</figcaption>
 <ol reversed>
  <li><cite>Josie and the Pussycats</cite>, 2001</li>
  <li><cite lang="sh">Црна мачка, бели мачор</cite>, 1998</li>
  <li><cite>A Bug's Life</cite>, 1998</li>
  <li><cite>Toy Story</cite>, 1995</li>
  <li><cite>Monsters, Inc</cite>, 2001</li>
  <li><cite>Cars</cite>, 2006</li>
  <li><cite>Toy Story 2</cite>, 1999</li>
  <li><cite>Finding Nemo</cite>, 2003</li>
  <li><cite>The Incredibles</cite>, 2004</li>
  <li><cite>Ratatouille</cite>, 2007</li>
 </ol>
</figure>

While it is conforming to include heading elements (e.g. h1) inside li elements, it likely does not convey the semantics that the author intended. A heading starts a new section, so a heading in a list implicitly splits the list into spanning multiple sections.

4.4.8 The `dl` element

If the element's children include at least one name-value group: Palpable content.

Where flow content is expected.

Zero or more groups each consisting of one or more dt elements followed by one or more dd elements, optionally intermixed with script-supporting elements.

Neither tag is omissible.

Allowed ARIA role attribute values:

Any aria-* attributes applicable to the allowed roles.

interface HTMLDListElement : HTMLElement {
  // also has obsolete members
};

The dl element represents an association list consisting of zero or more name-value groups (a description list). A name-value group consists of one or more names (dt elements) followed by one or more values (dd elements), ignoring any nodes other than dt and dd elements. Within a single dl element, there should not be more than one dt element for each name.

Name-value groups may be terms and definitions, metadata topics and values, questions and answers, or any other groups of name-value data.

The values within a group are alternatives; multiple paragraphs forming part of the same value must all be given within the same dd element.

The order of the list of groups, and of the names and values within each group, may be significant.

If a dl element has no dt or dd element children, it contains no groups.

If a dl element has one or more non-whitespace Text node children, or has child elements that are neither dt nor dd elements, all such Text nodes and elements, as well as their descendants (including any dt or dd elements), do not form part of any groups in that dl.

If a dl element has one or more dt element children but no dd element children, then it consists of one group with names but no values.

If a dl element has one or more dd element children but no dt element children, then it consists of one group with values but no names.

If a dl element's first dt or dd element child is a dd element, then the first group has no associated name.

If a dl element's last dt or dd element child is a dt element, then the last group has no associated value.

When a dl element doesn't match its content model, it is often due to accidentally using dd elements in the place of dt elements and vice versa. Conformance checkers can spot such mistakes and might be able to advise authors how to correctly use the markup.

In the following example, one entry ("Authors") is linked to two values ("John" and "Luke").

<dl>
 <dt> Authors
 <dd> John
 <dd> Luke
 <dt> Editor
 <dd> Frank
</dl>

In the following example, one definition is linked to two terms.

<dl>
 <dt lang="en-US"> <dfn>color</dfn> </dt>
 <dt lang="en-GB"> <dfn>colour</dfn> </dt>
 <dd> A sensation which (in humans) derives from the ability of
 the fine structure of the eye to distinguish three differently
 filtered analyses of a view. </dd>
</dl>

The following example illustrates the use of the dl element to mark up metadata of sorts. At the end of the example, one group has two metadata labels ("Authors" and "Editors") and two values ("Robert Rothman" and "Daniel Jackson").

<dl>
 <dt> Last modified time </dt>
 <dd> 2004-12-23T23:33Z </dd>
 <dt> Recommended update interval </dt>
 <dd> 60s </dd>
 <dt> Authors </dt>
 <dt> Editors </dt>
 <dd> Robert Rothman </dd>
 <dd> Daniel Jackson </dd>
</dl>

The following example shows the dl element used to give a set of instructions. The order of the instructions here is important (in the other examples, the order of the blocks was not important).

<p>Determine the victory points as follows (use the
first matching case):</p>
<dl>
 <dt> If you have exactly five gold coins </dt>
 <dd> You get five victory points </dd>
 <dt> If you have one or more gold coins, and you have one or more silver coins </dt>
 <dd> You get two victory points </dd>
 <dt> If you have one or more silver coins </dt>
 <dd> You get one victory point </dd>
 <dt> Otherwise </dt>
 <dd> You get no victory points </dd>
</dl>

The following snippet shows a dl element being used as a glossary. Note the use of dfn to indicate the word being defined.

<dl>
 <dt><dfn>Apartment</dfn>, n.</dt>
 <dd>An execution context grouping one or more threads with one or
 more COM objects.</dd>
 <dt><dfn>Flat</dfn>, n.</dt>
 <dd>A deflated tire.</dd>
 <dt><dfn>Home</dfn>, n.</dt>
 <dd>The user's login directory.</dd>
</dl>

The dl element is inappropriate for marking up dialogue. Examples of how to mark up dialogue are shown below.

4.4.9 The `dt` element

Categories:: None.
Contexts in which this element can be used:: Before dd or dt elements inside dl elements.
Content model:: Flow content, but with no header, footer, sectioning content, or heading content descendants.
Tag omission in text/html:: A dt element's end tag can be omitted if the dt element is immediately followed by another dt element or a dd element.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The dt element represents the term, or name, part of a term-description group in a description list (dl element).

The dt element itself, when used in a dl element, does not indicate that its contents are a term being defined, but this can be indicated using the dfn element.

This example shows a list of frequently asked questions (a FAQ) marked up using the dt element for questions and the dd element for answers.

<article>
 <h1>FAQ</h1>
 <dl>
  <dt>What do we want?</dt>
  <dd>Our data.</dd>
  <dt>When do we want it?</dt>
  <dd>Now.</dd>
  <dt>Where is it?</dt>
  <dd>We are not sure.</dd>
 </dl>
</article>

4.4.10 The `dd` element

Categories:: None.
Contexts in which this element can be used:: After dt or dd elements inside dl elements.
Content model:: Flow content.
Tag omission in text/html:: A dd element's end tag can be omitted if the dd element is immediately followed by another dd element or a dt element, or if there is no more content in the parent element.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The dd element represents the description, definition, or value, part of a term-description group in a description list (dl element).

A dl can be used to define a vocabulary list, like in a dictionary. In the following example, each entry, given by a dt with a dfn, has several dds, showing the various parts of the definition.

<dl>
 <dt><dfn>happiness</dfn></dt>
 <dd class="pronunciation">/'hæ p. nes/</dd>
 <dd class="part-of-speech"><i><abbr>n.</abbr></i></dd>
 <dd>The state of being happy.</dd>
 <dd>Good fortune; success. <q>Oh <b>happiness</b>! It worked!</q></dd>
 <dt><dfn>rejoice</dfn></dt>
 <dd class="pronunciation">/ri jois'/</dd>
 <dd><i class="part-of-speech"><abbr>v.intr.</abbr></i> To be delighted oneself.</dd>
 <dd><i class="part-of-speech"><abbr>v.tr.</abbr></i> To cause one to be delighted.</dd>
</dl>

4.4.11 The `figure` element

Categories:: Flow content.; Sectioning root.; Palpable content.
Contexts in which this element can be used:: Where flow content is expected.
Content model:: Either: One figcaption element followed by flow content.; Or: Flow content followed by one figcaption element.; Or: Flow content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The figure element represents some flow content, optionally with a caption, that is self-contained (like a complete sentence) and is typically referenced as a single unit from the main flow of the document.

Self-contained in this context does not necessarily mean independent. For example, each sentence in a paragraph is self-contained; an image that is part of a sentence would be inappropriate for figure, but an entire sentence made of images would be fitting.

The element can thus be used to annotate illustrations, diagrams, photos, code listings, etc.

When a figure is referred to from the main content of the document by identifying it by its caption (e.g. by figure number), it enables such content to be easily moved away from that primary content, e.g. to the side of the page, to dedicated pages, or to an appendix, without affecting the flow of the document.

If a figure element is referenced by its relative position, e.g. "in the photograph above" or "as the next figure shows", then moving the figure would disrupt the page's meaning. Authors are encouraged to consider using labels to refer to figures, rather than using such relative references, so that the page can easily be restyled without affecting the page's meaning.

The first figcaption element child of the element, if any, represents the caption of the figure element's contents. If there is no child figcaption element, then there is no caption.

A figure element's contents are part of the surrounding flow. If the purpose of the page is to display the figure, for example a photograph on an image sharing site, the figure and figcaption elements can be used to explicitly provide a caption for that figure. For content that is only tangentially related, or that serves a separate purpose than the surrounding flow, the aside element should be used (and can itself wrap a figure). For example, a pull quote that repeats content from an article would be more appropriate in an aside than in a figure, because it isn't part of the content, it's a repetition of the content for the purposes of enticing readers or highlighting key topics.

This example shows the figure element to mark up a code listing.

<p>In <a href="#l4">listing 4</a> we see the primary core interface
API declaration.</p>
<figure id="l4">
 <figcaption>Listing 4. The primary core interface API declaration.</figcaption>
 <pre><code>interface PrimaryCore {
 boolean verifyDataLine();
 void sendData(in sequence&lt;byte> data);
 void initSelfDestruct();
}</code></pre>
</figure>
<p>The API is designed to use UTF-8.</p>

Here we see a figure element to mark up a photo that is the main content of the page (as in a gallery).

<!DOCTYPE HTML>
<title>Bubbles at work — My Gallery™</title>
<figure>
 <img src="bubbles-work.jpeg"
      alt="Bubbles, sitting in his office chair, works on his
           latest project intently.">
 <figcaption>Bubbles at work</figcaption>
</figure>
<nav><a href="19414.html">Prev</a> — <a href="19416.html">Next</a></nav>

In this example, we see an image that is not a figure, as well as an image and a video that are. The first image is literally part of the example's second sentence, so it's not a self-contained unit, and thus figure would be inappropriate.

<h2>Malinko's comics</h2>

<p>This case centered on some sort of "intellectual property"
infringement related to a comic (see Exhibit A). The suit started
after a trailer ending with these words:

<blockquote>
 <img src="promblem-packed-action.png" alt="ROUGH COPY! Promblem-Packed Action!">
</blockquote>

<p>...was aired. A lawyer, armed with a Bigger Notebook, launched a
preemptive strike using snowballs. A complete copy of the trailer is
included with Exhibit B.

<figure>
 <img src="ex-a.png" alt="Two squiggles on a dirty piece of paper.">
 <figcaption>Exhibit A. The alleged <cite>rough copy</cite> comic.</figcaption>
</figure>

<figure>
 <video src="ex-b.mov"></video>
 <figcaption>Exhibit B. The <cite>Rough Copy</cite> trailer.</figcaption>
</figure>

<p>The case was resolved out of court.

Here, a part of a poem is marked up using figure.

<figure>
 <p>'Twas brillig, and the slithy toves<br>
 Did gyre and gimble in the wabe;<br>
 All mimsy were the borogoves,<br>
 And the mome raths outgrabe.</p>
 <figcaption><cite>Jabberwocky</cite> (first verse). Lewis Carroll, 1832-98</figcaption>
</figure>

In this example, which could be part of a much larger work discussing a castle, nested figure elements are used to provide both a group caption and individual captions for each figure in the group:

<figure>
 <figcaption>The castle through the ages: 1423, 1858, and 1999 respectively.</figcaption>
 <figure>
  <figcaption>Etching. Anonymous, ca. 1423.</figcaption>
  <img src="castle1423.jpeg" alt="The castle has one tower, and a tall wall around it.">
 </figure>
 <figure>
  <figcaption>Oil-based paint on canvas. Maria Towle, 1858.</figcaption>
  <img src="castle1858.jpeg" alt="The castle now has two towers and two walls.">
 </figure>
 <figure>
  <figcaption>Film photograph. Peter Jankle, 1999.</figcaption>
  <img src="castle1999.jpeg" alt="The castle lies in ruins, the original tower all that remains in one piece.">
 </figure>
</figure>

The previous example could also be more succintly written as follows (using title attributes in place of the nested figure/figcaption pairs):

<figure>
 <img src="castle1423.jpeg" title="Etching. Anonymous, ca. 1423."
      alt="The castle has one tower, and a tall wall around it.">
 <img src="castle1858.jpeg" title="Oil-based paint on canvas. Maria Towle, 1858."
      alt="The castle now has two towers and two walls.">
 <img src="castle1999.jpeg" title="Film photograph. Peter Jankle, 1999."
      alt="The castle lies in ruins, the original tower all that remains in one piece.">
 <figcaption>The castle through the ages: 1423, 1858, and 1999 respectively.</figcaption>
</figure>

The figure is sometimes referenced only implicitly from the content:

<article>
 <h1>Fiscal negotiations stumble in Congress as deadline nears</h1>
 <figure>
  <img src="obama-reid.jpeg" alt="Obama and Reid sit together smiling in the Oval Office.">
  <figcaption>Barrak Obama and Harry Reid. White House press photograph.</figcaption>
 </figure>
 <p>Negotiations in Congress to end the fiscal impasse sputtered on Tuesday, leaving both chambers
 grasping for a way to reopen the government and raise the country's borrowing authority with a
 Thursday deadline drawing near.</p>
 ...
</article>

4.4.12 The `figcaption` element

Categories:: None.
Contexts in which this element can be used:: As the first or last child of a figure element.
Content model:: Flow content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The figcaption element represents a caption or legend for the rest of the contents of the figcaption element's parent figure element, if any.

4.4.13 The `main` element

Categories:: Flow content.; Palpable content.
Contexts in which this element can be used:: Where flow content is expected, but with no article, aside, footer, header or nav element ancestors.
Content model:: Flow content.
Content attributes:: Global attributes
Tag omission in text/html:: Neither tag is omissible
Allowed ARIA role attribute values:: main role (default - do not set) or presentation.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement

The main element represents the main content of the body of a document or application. The main content area consists of content that is directly related to or expands upon the central topic of a document or central functionality of an application.

The main element is not sectioning content and has no effect on the document outline

The main content area of a document includes content that is unique to that document and excludes content that is repeated across a set of documents such as site navigation links, copyright information, site logos and banners and search forms (unless the document or applications main function is that of a search form).

User agents that support keyboard navigation of content are strongly encouraged to provide a method to navigate to the main element and once navigated to, ensure the next element in the focus order is the first focusable element within the main element. This will provide a simple method for keyboard users to bypass blocks of content such as navigation links.

Authors must not include more than one main element in a document.

Authors must not include the main element as a descendant of an article, aside, footer, header or nav element.

The main element is not suitable for use to identify the main content areas of sub sections of a document or application. The simplest solution is to not mark up the main content of a sub section at all, and just leave it as implicit, but an author could use a grouping content or sectioning content element as appropriate.

In the following example, we see 2 articles about skateboards (the main topic of a Web page) the main topic content is identified by the use of the main element.

<!-- other content -->

<main>

  <h1>Skateboards</h1>
  <p>The skateboard is the way cool kids get around</p>

  <article>
  <h2>Longboards</h2>
  <p>Longboards are a type of skateboard with a longer
  wheelbase and larger, softer wheels.</p>
  <p>... </p>
  <p>... </p>
  </article>

  <article>
  <h2>Electric Skateboards</h2>
  <p>These no longer require the propelling of the skateboard
  by means of the feet; rather an electric motor propels the board,
  fed by an electric battery.</p>
  <p>... </p>
  <p>... </p>
  </article>

</main>

  <!-- other content -->

Here is a graduation programme where the main content section is defined by the use of the main element. Note in this example the main element contains a nav element consisting of links to sub sections of the main content.

<!DOCTYPE html>
  <html lang="en">
  <head>
<title>Graduation Ceremony Summer 2022</title>
  </head>
  <body>

  <header>The Lawson Academy:
  <nav>
  <ul>
  <li><a href="courses.html">Courses</a></li>
  <li><a href="fees.html">Fees</a></li>
  <li><a>Graduation</a></li>
  </ul>
  </nav>
  </header>


<main>


  <h1>Graduation</h1>

  <nav>
  <ul>
  <li><a href="#ceremony">Ceremony</a></li>
  <li><a href="#graduates">Graduates</a></li>
  <li><a href="#awards">Awards</a></li>
  </ul>
  </nav>

  <H2 id="ceremony">Ceremony</H2>
  <p>Opening Procession</p>
  <p>Speech by Valedictorian</p>
  <p>Speech by Class President</p>
  <p>Presentation of Diplomas</p>
  <p>Closing Speech by Headmaster</p>

  <h2 id="graduates">Graduates</h2>
  <ul>
  <li>Eileen Williams</li>
  <li>Andy Maseyk</li>
  <li>Blanca Sainz Garcia</li>
  <li>Clara Faulkner</li>
  <li>Gez Lemon</li>
  <li>Eloisa Faulkner</li>
  </ul>

  <h2 id="awards">Awards</h2>
  <ul>
  <li>Clara Faulkner</li>
  <li>Eloisa Faulkner</li>
  <li>Blanca Sainz Garcia</li>
  </ul>

</main>

  <footer> Copyright 2012 B.lawson</footer>

  </body>
  </html>

4.4.14 The `div` element

Where flow content is expected.

Neither tag is omissible.

Allowed ARIA role attribute values:

Any aria-* attributes applicable to the allowed roles.

interface HTMLDivElement : HTMLElement {
  // also has obsolete members
};

The div element has no special meaning at all. It represents its children. It can be used with the class, lang, and title attributes to mark up semantics common to a group of consecutive elements.

Authors are strongly encouraged to view the div element as an element of last resort, for when no other element is suitable. Use of more appropriate elements instead of the div element leads to better accessibility for readers and easier maintainability for authors.

For example, a blog post would be marked up using article, a chapter using section, a page's navigation aids using nav, and a group of form controls using fieldset.

On the other hand, div elements can be useful for stylistic purposes or to wrap multiple paragraphs within a section that are all to be annotated in a similar way. In the following example, we see div elements used as a way to set the language of two paragraphs at once, instead of setting the language on the two paragraph elements separately:

<article lang="en-US">
 <h1>My use of language and my cats</h1>
 <p>My cat's behaviour hasn't changed much since her absence, except
 that she plays her new physique to the neighbors regularly, in an
 attempt to get pets.</p>
 <div lang="en-GB">
  <p>My other cat, coloured black and white, is a sweetie. He followed
  us to the pool today, walking down the pavement with us. Yesterday
  he apparently visited our neighbours. I wonder if he recognises that
  their flat is a mirror image of ours.</p>
  <p>Hm, I just noticed that in the last paragraph I used British
  English. But I'm supposed to write in American English. So I
  shouldn't say "pavement" or "flat" or "colour"...</p>
 </div>
 <p>I should say "sidewalk" and "apartment" and "color"!</p>
</article>

4.5 Text-level semantics

4.5.1 The `a` element

Where phrasing content is expected.

Transparent, but there must be no interactive content descendant.

Neither tag is omissible.

href — Address of the hyperlink

target — Browsing context for hyperlink navigation

download — Whether to download the resource instead of navigating to it, and its file name if so

rel — Relationship between the document containing the hyperlink and the destination resource

hreflang — Language of the linked resource

type — Hint for the type of the referenced resource

Allowed ARIA role attribute values:

link (default - do not set), button, checkbox, menuitem, menuitemcheckbox, menuitemradio, tab or treeitem

Any aria-* attributes applicable to the allowed roles.

interface HTMLAnchorElement : HTMLElement {
  attribute DOMString target;
  attribute DOMString download;
  attribute DOMString rel;
  readonly attribute DOMTokenList relList;
  attribute DOMString hreflang;
  attribute DOMString type;

  attribute DOMString text;

  // also has obsolete members
};
HTMLAnchorElement implements HTMLHyperlinkElementUtils;

If the a element has an href attribute, then it represents a hyperlink (a hypertext anchor) labeled by its contents.

If the a element has no href attribute, then the element represents a placeholder for where a link might otherwise have been placed, if it had been relevant, consisting of just the element's contents.

The target, download, rel, hreflang, and type attributes must be omitted if the href attribute is not present.

If the itemprop attribute is specified on an a element, then the href attribute must also be specified.

If a site uses a consistent navigation toolbar on every page, then the link that would normally link to the page itself could be marked up using an a element:

<nav>
 <ul>
  <li> <a href="/">Home</a> </li>
  <li> <a href="/news">News</a> </li>
  <li> <a>Examples</a> </li>
  <li> <a href="/legal">Legal</a> </li>
 </ul>
</nav>

The href, target, download attributes affect what happens when users follow hyperlinks or download hyperlinks created using the a element. The rel, hreflang, and type attributes may be used to indicate to the user the likely nature of the target resource before the user follows the link.

The activation behaviour of a elements that create hyperlinks is to run the following steps:

If the a element's node document is not fully active, then abort these steps.
If either the a element has a download attribute and the algorithm is not allowed to show a popup; or, if the user has not indicated a specific browsing context for following the link, and the element's target attribute is present, and applying the rules for choosing a browsing context given a browsing context name, using the value of the target attribute as the browsing context name, would result in there not being a chosen browsing context, then run these substeps:
1. If there is an entry settings object, throw an InvalidAccessError exception.
2. Abort these steps without following the hyperlink.
If the target of the click event is an img element with an ismap attribute specified, then server-side image map processing must be performed, as follows:
1. If the click event was a real pointing-device-triggered click event on the img element, then let x be the distance in CSS pixels from the left edge of the image's left border, if it has one, or the left edge of the image otherwise, to the location of the click, and let y be the distance in CSS pixels from the top edge of the image's top border, if it has one, or the top edge of the image otherwise, to the location of the click. Otherwise, let x and y be zero.
2. Let the hyperlink suffix be a U+003F QUESTION MARK character, the value of x expressed as a base-ten integer using ASCII digits, a U+002C COMMA character (,), and the value of y expressed as a base-ten integer using ASCII digits.
Finally, the user agent must follow the hyperlink or download the hyperlink created by the a element, as determined by the download attribute and any expressed user preference. If the steps above defined a hyperlink suffix, then take that into account when following or downloading the hyperlink.

a . text: Same as textContent.

The IDL attributes download, target, rel, hreflang, and type, must reflect the respective content attributes of the same name.

The IDL attribute relList must reflect the rel content attribute.

The text IDL attribute, on getting, must return the same value as the textContent IDL attribute on the element, and on setting, must act as if the textContent IDL attribute on the element had been set to the new value.

The a element may be wrapped around entire paragraphs, lists, tables, and so forth, even entire sections, so long as there is no interactive content within (e.g. buttons or other links). This example shows how this can be used to make an entire advertising block into a link:

<aside class="advertising">
 <h1>Advertising</h1>
 <a href="http://ad.example.com/?adid=1929&amp;pubid=1422">
  <section>
   <h1>Mellblomatic 9000!</h1>
   <p>Turn all your widgets into mellbloms!</p>
   <p>Only $9.99 plus shipping and handling.</p>
  </section>
 </a>
 <a href="http://ad.example.com/?adid=375&amp;pubid=1422">
  <section>
   <h1>The Mellblom Browser</h1>
   <p>Web browsing at the speed of light.</p>
   <p>No other browser goes faster!</p>
  </section>
 </a>
</aside>

4.5.2 The `em` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The em element represents stress emphasis of its contents.

The level of stress that a particular piece of content has is given by its number of ancestor em elements.

The placement of stress emphasis changes the meaning of the sentence. The element thus forms an integral part of the content. The precise way in which stress is used in this way depends on the language.

These examples show how changing the stress emphasis changes the meaning. First, a general statement of fact, with no stress:

<p>Cats are cute animals.</p>

By emphasizing the first word, the statement implies that the kind of animal under discussion is in question (maybe someone is asserting that dogs are cute):

<p><em>Cats</em> are cute animals.</p>

Moving the stress to the verb, one highlights that the truth of the entire sentence is in question (maybe someone is saying cats are not cute):

<p>Cats <em>are</em> cute animals.</p>

By moving it to the adjective, the exact nature of the cats is reasserted (maybe someone suggested cats were mean animals):

<p>Cats are <em>cute</em> animals.</p>

Similarly, if someone asserted that cats were vegetables, someone correcting this might emphasise the last word:

<p>Cats are cute <em>animals</em>.</p>

By emphasizing the entire sentence, it becomes clear that the speaker is fighting hard to get the point across. This kind of stress emphasis also typically affects the punctuation, hence the exclamation mark here.

<p><em>Cats are cute animals!</em></p>

Anger mixed with emphasizing the cuteness could lead to markup such as:

<p><em>Cats are <em>cute</em> animals!</em></p>

The em element isn't a generic "italics" element. Sometimes, text is intended to stand out from the rest of the paragraph, as if it was in a different mood or voice. For this, the i element is more appropriate.

The em element also isn't intended to convey importance; for that purpose, the strong element is more appropriate.

4.5.3 The `strong` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The strong element represents strong importance, seriousness, or urgency for its contents.

Importance: The strong element can be used in a heading, caption, or paragraph to distinguish the part that really matters from other parts that might be more detailed, more jovial, or merely boilerplate.

For example, the first word of the previous paragraph is marked up with strong to distinguish it from the more detailed text in the rest of the paragraph.

Seriousness: The strong element can be used to mark up a warning or caution notice.

Urgency: The strong element can be used to denote contents that the user needs to see sooner than other parts of the document.

The relative level of importance of a piece of content is given by its number of ancestor strong elements; each strong element increases the importance of its contents.

Changing the importance of a piece of text with the strong element does not change the meaning of the sentence.

Here, the word "chapter" and the actual chapter number are mere boilerplate, and the actual name of the chapter is marked up with strong:

<h1>Chapter 1: <strong>The Praxis</strong></h1>

In the following example, the name of the diagram in the caption is marked up with strong, to distinguish it from boilerplate text (before) and the description (after):

<figcaption>Figure 1. <strong>Ant colony dynamics</strong>. The ants in this colony are
affected by the heat source (upper left) and the food source (lower right).</figcaption>

In this example, the heading is really "Flowers, Bees, and Honey", but the author has added a light-hearted addition to the heading. The strong element is thus used to mark up the first part to distinguish it from the latter part.

<h1><strong>Flowers, Bees, and Honey</strong> and other things I don't understand</h1>

Here is an example of a warning notice in a game, with the various parts marked up according to how important they are:

<p><strong>Warning.</strong> This dungeon is dangerous.
<strong>Avoid the ducks.</strong> Take any gold you find.
<strong><strong>Do not take any of the diamonds</strong>,
they are explosive and <strong>will destroy anything within
ten meters.</strong></strong> You have been warned.</p>

In this example, the strong element is used to denote the part of the text that the user is intended to read first.

<p>Welcome to Remy, the reminder system.</p>
<p>Your tasks for today:</p>
<ul>
 <li><p><strong>Turn off the oven.</strong></p></li>
 <li><p>Put out the trash.</p></li>
 <li><p>Do the laundry.</p></li>
</ul>

4.5.4 The `small` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The small element represents side comments such as small print.

Small print typically features disclaimers, caveats, legal restrictions, or copyrights. Small print is also sometimes used for attribution, or for satisfying licensing requirements.

The small element does not "de-emphasize" or lower the importance of text emphasized by the em element or marked as important with the strong element. To mark text as not emphasized or important, simply do not mark it up with the em or strong elements respectively.

The small element should not be used for extended spans of text, such as multiple paragraphs, lists, or sections of text. It is only intended for short runs of text. The text of a page listing terms of use, for instance, would not be a suitable candidate for the small element: in such a case, the text is not a side comment, it is the main content of the page.

The small element must not be used for subheadings.

In this example, the small element is used to indicate that value-added tax is not included in a price of a hotel room:

<dl>
 <dt>Single room
 <dd>199 € <small>breakfast included, VAT not included</small>
 <dt>Double room
 <dd>239 € <small>breakfast included, VAT not included</small>
</dl>

In this second example, the small element is used for a side comment in an article.

<p>Example Corp today announced record profits for the
second quarter <small>(Full Disclosure: Foo News is a subsidiary of
Example Corp)</small>, leading to speculation about a third quarter
merger with Demo Group.</p>

This is distinct from a sidebar, which might be multiple paragraphs long and is removed from the main flow of text. In the following example, we see a sidebar from the same article. This sidebar also has small print, indicating the source of the information in the sidebar.

<aside>
 <h1>Example Corp</h1>
 <p>This company mostly creates small software and Web
 sites.</p>
 <p>The Example Corp company mission is "To provide entertainment
 and news on a sample basis".</p>
 <p><small>Information obtained from <a
 href="http://example.com/about.html">example.com</a> home
 page.</small></p>
</aside>

In this last example, the small element is marked as being important small print.

<p><strong><small>Continued use of this service will result in a kiss.</small></strong></p>

4.5.5 The `s` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The s element represents contents that are no longer accurate or no longer relevant.

The s element is not appropriate when indicating document edits; to mark a span of text as having been removed from a document, use the del element.

In this example a recommended retail price has been marked as no longer relevant as the product in question has a new sale price.

<p>Buy our Iced Tea and Lemonade!</p>
<p><s>Recommended retail price: $3.99 per bottle</s></p>
<p><strong>Now selling for just $2.99 a bottle!</strong></p>

4.5.6 The `cite` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Content attributes:: Global attributes
Tag omission in text/html:: Neither tag is omissible
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The cite element represents a reference to a creative work. It must include the title of the work or the name of the author(person, people or organization) or an URL reference, or a reference in abbreviated form as per the conventions used for the addition of citation metadata.

Creative works include a book, a paper, an essay, a poem, a score, a song, a script, a film, a TV show, a game, a sculpture, a painting, a theatre production, a play, an opera, a musical, an exhibition, a legal case report, a computer program, , a web site, a web page, a blog post or comment, a forum post or comment, a tweet, a written or oral statement, etc.

Here is an example of the author of a quote referenced using the cite element:

  
  <p>In the words of <cite>Charles Bukowski</cite> -  
  <q>An intellectual says a simple thing in a hard way. An artist says a hard thing in a simple way.</q></p>

This second example identifies the author of a tweet by referencing the authors name using the cite element:

  
  <blockquote class="twitter-tweet">
  <p>♥ Bukowski in <a href="https://twitter.com/search?q=%23HTML5&src=hash">#HTML5</a> spec examples
  <a href="http://t.co/0FIEiYN1pC">http://t.co/0FIEiYN1pC</a></p><cite>— karl dubost (@karlpro) 
  <a href="https://twitter.com/karlpro/statuses/370905307293442048">August 23, 2013</a></cite>
  </blockquote>

In this example the cite element is used to reference the title of a work in a bibliography:

<p><cite>Universal Declaration of Human Rights</cite>, United Nations,
December 1948. Adopted by General Assembly resolution 217 A (III).</p>

In this example the cite element is used to reference the title of a television show:

<p>Who is your favorite doctor (in <cite>Doctor Who</cite>)?</p>

A very common use for the cite element is to identify the author of a comment in a blog post or forum, as in this example:

  <article id="comment-1"> 
  Comment by <cite><a href="http://oli.jp">Oli Studholme</a></cite> 
  <time datetime="2013-08-19T16:01">August 19th, 2013 at 4:01 pm</time>
  <p>Unfortunately I don't think adding names back into the definition of <code>cite</code>
  solves the problem: of the 12 blockquote examples in
  <a href="http://oli.jp/example/blockquote-metadata/">Examples of block quote metadata</a>,
  there's not even one that's <em>just</em> a person’s name.</p>
  <p>A subset of the problem, maybe…</p>
  </article>

Another common use for the cite element is to reference the URL of a search result, as in this example:

  <div id="resultStats">About 416,000,000 results 0.33 seconds) </div>
  ...
  <p><a href="http://www.w3.org/html/wg/">W3C <i>HTML Working Group</i></a></p>
  <p><cite>www.w3.org/<b>html</b>/wg/</cite></p>
  <p>15 Apr 2013 - The <i>HTML Working Group</i> is currently chartered to continue its 
  work through 31 December 2014. A Plan 2014 document published by the...</p>
  ...

Where the cite element is used to identify an abbreviated reference such as Ibid. it is suggested that this reference be linked to the base reference:

  <article>
  <h2>Book notes</h2>
  ...
  ...
  <blockquote>"Money is the real cause of poverty," 
  <footer> 
  <cite id="baseref">The Ragged-Trousered Philanthropists, page 89.</cite>
  </footer>
  </blockquote>
  ...
  ...
  <blockquote>"Money is the cause of poverty because it is the device by which those who 
  are too lazy to work are enabled to rob the workers of the fruits of their labour."
  <a href="#baseref"><cite>Ibid.</cite></a> 
  </blockquote>
  ...
  </article>

A citation is not a quote (for which the q element is appropriate).

This is incorrect usage, because cite is not for quotes:

<p><cite>This is wrong!, said Hillary.</cite> is a quote from the
  popular daytime TV drama When Ian became Hillary.</p>

This is an example of the correct usage:

<p><q>This is correct, said Hillary.</q> is a quote from the
  popular daytime TV drama <cite>When Ian became Hillary</cite>.</p>

4.5.7 The `q` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes; cite — Link to the source of the quotation or more information about the edit
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLQuoteElement.

The q element represents some phrasing content quoted from another source.

Quotation punctuation (such as quotation marks) that is quoting the contents of the element must not appear immediately before, after, or inside q elements; they will be inserted into the rendering by the user agent.

Content inside a q element must be quoted from another source, whose address, if it has one, may be cited in the cite attribute. The source may be fictional, as when quoting characters in a novel or screenplay.

The q element must not be used in place of quotation marks that do not represent quotes; for example, it is inappropriate to use the q element for marking up sarcastic statements.

The use of q elements to mark up quotations is entirely optional; using explicit quotation punctuation without q elements is just as correct.

Here is a simple example of the use of the q element:

<p>The man said <q>Things that are impossible just take
longer</q>. I disagreed with him.</p>

Here is an example with both an explicit citation link in the q element, and an explicit citation outside:

<p>The W3C page <cite>About W3C</cite> says the W3C's
mission is <q cite="http://www.w3.org/Consortium/">To lead the
World Wide Web to its full potential by developing protocols and
guidelines that ensure long-term growth for the Web</q>. I
disagree with this mission.</p>

In the following example, the quotation itself contains a quotation:

<p>In <cite>Example One</cite>, he writes <q>The man
said <q>Things that are impossible just take longer</q>. I
disagreed with him</q>. Well, I disagree even more!</p>

In the following example, quotation marks are used instead of the q element:

<p>His best argument was ❝I disagree❞, which
I thought was laughable.</p>

In the following example, there is no quote — the quotation marks are used to name a word. Use of the q element in this case would be inappropriate.

<p>The word "ineffable" could have been used to describe the disaster
resulting from the campaign's mismanagement.</p>

4.5.8 The `dfn` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content, but there must be no dfn element descendants.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes; Also, the title attribute has special semantics on this element: Full term or expansion of abbreviation.
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The dfn element represents the defining instance of a term. The paragraph, description list group, or section that is the nearest ancestor of the dfn element must also contain the definition(s) for the term given by the dfn element.

Defining term: If the dfn element has a title attribute, then the exact value of that attribute is the term being defined. Otherwise, if it contains exactly one element child node and no child Text nodes, and that child element is an abbr element with a title attribute, then the exact value of that attribute is the term being defined. Otherwise, it is the exact textContent of the dfn element that gives the term being defined.

If the title attribute of the dfn element is present, then it must contain only the term being defined.

The title attribute of ancestor elements does not affect dfn elements.

An a element that links to a dfn element represents an instance of the term defined by the dfn element.

In the following fragment, the term "Garage Door Opener" is first defined in the first paragraph, then used in the second. In both cases, its abbreviation is what is actually displayed.

<p>The <dfn><abbr title="Garage Door Opener">GDO</abbr></dfn>
is a device that allows off-world teams to open the iris.</p>
<!-- ... later in the document: -->
<p>Teal'c activated his <abbr title="Garage Door Opener">GDO</abbr>
and so Hammond ordered the iris to be opened.</p>

With the addition of an a element, the reference can be made explicit:

<p>The <dfn id=gdo><abbr title="Garage Door Opener">GDO</abbr></dfn>
is a device that allows off-world teams to open the iris.</p>
<!-- ... later in the document: -->
<p>Teal'c activated his <a href=#gdo><abbr title="Garage Door Opener">GDO</abbr></a>
and so Hammond ordered the iris to be opened.</p>

4.5.9 The `abbr` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes; Also, the title attribute has special semantics on this element: Full term or expansion of abbreviation.
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The abbr element represents an abbreviation or acronym, optionally with its expansion. The title attribute may be used to provide an expansion of the abbreviation. The attribute, if specified, must contain an expansion of the abbreviation, and nothing else.

The paragraph below contains an abbreviation marked up with the abbr element. This paragraph defines the term "Web Hypertext Application Technology Working Group".

<p>The <dfn id=whatwg><abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr></dfn>
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.</p>

An alternative way to write this would be:

<p>The <dfn id=whatwg>Web Hypertext Application Technology
Working Group</dfn> (<abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr>)
is a loose unofficial collaboration of Web browser manufacturers and
interested parties who wish to develop new technologies designed to
allow authors to write and deploy Applications over the World Wide
Web.</p>

This paragraph has two abbreviations. Notice how only one is defined; the other, with no expansion associated with it, does not use the abbr element.

<p>The
<abbr title="Web Hypertext Application Technology Working Group">WHATWG</abbr>
started working on HTML5 in 2004.</p>

This paragraph links an abbreviation to its definition.

<p>The <a href="#whatwg"><abbr
title="Web Hypertext Application Technology Working Group">WHATWG</abbr></a>
community does not have much representation from Asia.</p>

This paragraph marks up an abbreviation without giving an expansion, possibly as a hook to apply styles for abbreviations (e.g. smallcaps).

<p>Philip` and Dashiva both denied that they were going to
get the issue counts from past revisions of the specification to
backfill the <abbr>WHATWG</abbr> issue graph.</p>

If an abbreviation is pluralized, the expansion's grammatical number (plural vs singular) must match the grammatical number of the contents of the element.

Here the plural is outside the element, so the expansion is in the singular:

<p>Two <abbr title="Working Group">WG</abbr>s worked on
this specification: the <abbr>WHATWG</abbr> and the
<abbr>HTMLWG</abbr>.</p>

Here the plural is inside the element, so the expansion is in the plural:

<p>Two <abbr title="Working Groups">WGs</abbr> worked on
this specification: the <abbr>WHATWG</abbr> and the
<abbr>HTMLWG</abbr>.</p>

Abbreviations do not have to be marked up using this element. It is expected to be useful in the following cases:

Abbreviations for which the author wants to give expansions, where using the abbr element with a title attribute is an alternative to including the expansion inline (e.g. in parentheses).
Abbreviations that are likely to be unfamiliar to the document's readers, for which authors are encouraged to either mark up the abbreviation using an abbr element with a title attribute or include the expansion inline in the text the first time the abbreviation is used.
Abbreviations whose presence needs to be semantically annotated, e.g. so that they can be identified from a style sheet and given specific styles, for which the abbr element can be used without a title attribute.

Providing an expansion in a title attribute once will not necessarily cause other abbr elements in the same document with the same contents but without a title attribute to behave as if they had the same expansion. Every abbr element is independent.

4.5.10 The `ruby` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: See prose.
Content attributes:: Global attributes
Tag omission in text/html:: Neither tag is omissible
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The ruby element allows one or more spans of phrasing content to be marked with ruby annotations. Ruby annotations are short runs of text presented alongside base text, primarily used in East Asian typography as a guide for pronunciation or to include other annotations. In Japanese, this form of typography is also known as furigana. Ruby text can appear on either side, and sometimes both sides, of the base text, and it is possible to control its position using CSS. A more complete introduction to ruby can be found in the Use Cases & Exploratory Approaches for Ruby Markup document as well as in CSS Ruby Module Level 1. [RUBY-UC] [CSSRUBY]

The content model of ruby elements consists of one or more of the following sequences:

One or more phrasing content nodes or rb elements.
One or more rt or rtc elements, each of which either immediately preceded or followed by an rp elements.

The ruby, rb, rtc, and rt elements can be used for a variety of kinds of annotations, including in particular (though by no means limited to) those described below. For more details on Japanese Ruby in particular, and how to render Ruby for Japanese, see Requirements for Japanese Text Layout. [JLREQ] The rp element can be used as fallback content when ruby rendering is not supported.

Mono-ruby for individual base characters

Annotations (the ruby text) are associated individually with each ideographic character (the base text). In Japanese this is typically hiragana or katakana characters used to provide readings of kanji characters.

<ruby>base<rt>annotation</ruby>

When no rb element is used, the base is implied, as above. But you can also make it explicit. This can be useful notably for styling, or when consecutive bases are to be treated as a group, as in the jukugo ruby example further down.

<ruby><rb>base<rt>annotation</ruby>

In the following example, notice how each annotation corresponds to a single base character.

<ruby>日<rt>に</rt></ruby><ruby>本<rt>ほん</rt></ruby>
<ruby>語<rt>ご</rt></ruby>で<ruby>書<rt>か</rt></ruby>
いた<ruby>作<rt>さく</rt></ruby><ruby>文<rt>ぶん</rt></ruby>です。

Ruby text interspersed in regular text provides structure akin to the following image:

An example of ruby text mixed up with regular text.

This example can also be written as follows, using one ruby element with two segments of base text and two annotations (one for each) rather than two back-to-back ruby elements each with one base text segment and annotation (as in the markup above):

<ruby>日<rt>に</rt>本<rt>ほん</rt>語<rt>ご</rt></ruby>
で<ruby>書<rt>か</rt></ruby>
いた<ruby>作<rt>さく</rt>文<rt>ぶん</rt></ruby>です。

Group ruby

Group ruby is often used where phonetic annotations don't map to discreet base characters, or for semantic glosses that span the whole base text. For example, the word "today" is written with the characters 今日, literally "this day". But it's pronounced きょう (kyou), which can't be broken down into a "this" part and a "day" part. In typical rendering, you can't split text that is annotated with group ruby; it has to wrap as a single unit onto the next line. When a ruby text annotation maps to a base that is comprised of more than one character, then that base is grouped.

The following group ruby:

Group ruby example with きょう annotating 今日

Can be marked up as follows:

<ruby>今日<rt>きょう</ruby>

Jukugo ruby

Jukugo refers to a Japanese compound noun, i.e. a word made up of more than one kanji character. Jukugo ruby is a term that is used not to describe ruby annotations over jukugo text, but rather to describe ruby with a behaviour slightly different from mono or group ruby. Jukugo ruby is similar to mono ruby, in that there is a strong association between ruby text and individual base characters, but the ruby text is typically rendered as grouped together over multiple ideographs when they are on the same line.

The distinction is captured in this example:

Example of jukugo ruby

Which can be marked up as follows:

<ruby>法<rb>華<rb>経<rt>ほ<rt>け<rt>きょう</ruby>

In this example, each rt element is paired with its respective rb element, the difference with an interleaved rb/rt approach being that the sequences of both base text and ruby annotations are implicitly placed in common containers so that the grouping information is captured.

For more details on Jukugo Ruby rendering, see Appendix F in the Requirements for Japanese Text Layout and Use Case C: Jukugo ruby in the Use Cases & Exploratory Approaches for Ruby Markup. [JLREQ] [RUBY-UC]

Inline ruby

In some contexts, for instance when the font size or line height are too small for ruby to be readable, it is desirable to inline the ruby annotation such that it appears in parentheses after the text it annotates. This also provides a convenient fallback strategy for user agents that do not support rendering ruby annotations.

Inlining takes grouping into account. For example, Tokyo is written with two kanji characters, 東, which is pronounced とう, and 京, which is pronounced きょう. Each base character should be annotated individually, but the fallback should be 東京(とうきょう) not 東(とう)京(きょう). This can be marked up as follows:

<ruby>東<rb>京<rt>とう<rt>きょう</ruby>

Note that the above markup will enable the usage of parentheses when inlining for browsers that support ruby layout, but for those that don't it will fail to provide parenthetical fallback. This is where the rp element is useful. It can be inserted into the above example to provide the appropriate fallback when ruby layout is not supported:

<ruby>東<rb>京<rp>(<rt>とう<rt>きょう<rp>)</ruby>

Text with both phonetic and semantic annotations (double-sided ruby)

Sometimes, ruby can be used to annotate a base twice.

In the following example, the Chinese word for San Francisco (旧金山, i.e. “old gold mountain”) is annotated both using pinyin to give the pronunciation, and with the original English.

San Francisco in Chinese, with both pinyin and the original English as annotations.

Which is marked up as follows:

<ruby><rb>旧<rb>金<rb>山<rt>jiù<rt>jīn<rt>shān<rtc>San Francisco</ruby>

In this example, a single base run of three base characters is annotated with three pinyin ruby text segments in a first (implicit) container, and an rtc element is introduced in order to provide a second single ruby text annotation being the city's English name.

We can also revisit our jukugo example above with 上手 ("skill") to show how it can be annotation in both kana and romaji phonetics while at the same time maintaining the pairing to bases and annotation grouping information.

上手 ("skill") annotated in both kana and romaji, shown in both jukugo and mono styles.

Which is marked up as follows:

<ruby><rb>上<rb>手<rt>じよう<rt>ず<rtc><rt>jou<rt>zu</ruby>

Text that is a direct child of the rtc element implicitly produces a ruby text segment as if it were contained in an rt element. In this contrived example, this is shown with some symbols that are given names in English and French with annotations intended to appear on either side of the base symbol.

<ruby>
  ♥<rt>Heart<rtc lang=fr>Cœur</rtc>
  ☘<rt>Shamrock<rtc lang=fr>Trèfle</rtc>
  ✶<rt>Star<rtc lang=fr>Étoile
</ruby>

Similarly, text directly inside a ruby element implicitly produces a ruby base as if it were contained in an rb element, and rt children of ruby are implicitly contained in an rtc container. In effect, the above example is equivalent (in meaning, though not in the DOM it produces) to the following:

<ruby>
  <rb>♥</rb><rtc><rt>Heart</rt></rtc><rtc lang=fr><rt>Cœur</rt></rtc>
  <rb>☘</rb><rtc><rt>Shamrock</rt></rtc><rtc lang=fr><rt>Trèfle</rt></rtc>
  <rb>✶</rb><rtc><rt>Star</rt></rtc><rtc lang=fr><rt>Étoile</rt></rtc>
</ruby>

Within a ruby element, content is parcelled into a series of ruby segments. Each ruby segment is described by:

Zero or more ruby bases, each of which is a DOM range that may contain phrasing content or an rb element.
A base range, that is a DOM range including all the bases. This is the ruby base container.
Zero or more ruby text containers which may correspond to explicit rtc elements, or to sequences of rt elements implicitly recognised as contained in an anonymous ruby text container.

Each ruby text container is described by zero or more ruby text annotations each of which is a DOM range that may contain phrasing content or an rt element, and an annotations range that is a range including all the annotations for that container. A ruby text container is also known (primarily in a CSS context) as a ruby annotation container.

Furthermore, a ruby element contains ignored ruby content. Ignored ruby content does not form part of the document's semantics. It consists of some inter-element whitespace and rp elements, the latter of which are used for legacy user agents that do not support ruby at all.

The process of annotation pairing associates ruby annotations with ruby bases. Within each ruby segment, each ruby base in the ruby base container is paired with one ruby text annotation from the ruby text container, in order. If there are not enough ruby text annotations in a ruby annotation container, the last one is associated with any excess ruby bases. (If there are not any in the ruby annotation container, an anonymous empty one is assumed to exist.) If there are not enough ruby bases, any remaining ruby text annotations are assumed to be associated with empty, anonymous bases inserted at the end of the ruby base container.

Note that the terms ruby segment, ruby base, ruby text annotation, ruby text container, ruby base container, and ruby annotation container have their equivalents in CSS Ruby Module Level 1. [CSSRUBY]

Informally, the segmentation and categorisation algorithm below performs a simple set of tasks. First it processes adjacent rb elements, text nodes, and non-ruby elements into a list of bases. Then it processes any number of rtc elements or sequences of rt elements that are considered to automatically map to an anonymous ruby text container. Put together these data items form a ruby segment as detailed in the data model above. It will continue to produce such segments until it reaches the end of the content of a given ruby element. The complexity of the algorithm below compared to this informal description stems from the need to support an author-friendly syntax and being mindful of inter-element white space.

At any particular time, the segmentation and categorisation of content of a ruby element is the result that would be obtained from running the following algorithm:

Let root be the ruby element for which the algorithm is being run.
Let index be 0.
Let ruby segments be an empty list.
Let current bases be an empty list of DOM ranges.
Let current bases range be null.
Let current bases range start be null.
Let current annotations be an empty list of DOM ranges.
Let current annotations range be null.
Let current annotations range start be null.
Let current annotation containers be an empty list.
Let current automatic base nodes be an empty list of DOM Nodes.
Let current automatic base range start be null.
Process a ruby child: If index is equal to or greater than the number of child nodes in root, then run the steps to commit a ruby segment, return ruby segments, and abort these steps.
Let current child be the indexth node in root.
If current child is not a Text node and is not an Element node, then increment index by one and jump to the step labelled process a ruby child.
If current child is an rp element, then increment index by one and jump to the step labelled process a ruby child. (Note that this has the effect of including this element in any range that we are currently processing. This is done intentionally so that misplaced rp can be processed correctly; semantically they are ignored all the same.)
If current child is an rt element, then run these substeps:
1. Run the steps to commit an automatic base.
2. Run the steps to commit the base range.
3. If current annotations is empty, set current annotations range start to the value of index.
4. Create a new DOM range whose start is the boundary point (root, index) and whose end is the boundary point (root, index plus one), and append it at the end of current annotations.
5. Increment index by one and jump to the step labelled process a ruby child.
If current child is an rtc element, then run these substeps:
1. Run the steps to commit an automatic base.
2. Run the steps to commit the base range.
3. Run the steps to commit current annotations.
4. Create a new ruby annotation container. It is described by the list of annotations returned by running the steps to process an rtc element and a DOM range whose start is the boundary point (root, index) and whose end is the boundary point (root, index plus one). Append this new ruby annotation container at the end of current annotation containers.
5. Increment index by one and jump to the step labelled process a ruby child.
If current child is a Text node and is inter-element whitespace, then run these substeps:
1. If current annotations is not empty, increment index by one and jump to the step labelled process a ruby child.
2. Run the following substeps:
  1. Let lookahead index be set to the value of index.
  2. Peek ahead: Increment lookahead index by one.
  3. If lookahead index is equal to or greater than the number of child nodes in root, then abort these substeps.
  4. Let peek child be the lookahead indexth node in root.
  5. If peek child is a Text node and is inter-element whitespace, then jump to the step labelled peek ahead.
  6. If peek child is an rt element, an rtc element, or an rp element, then set index to the value of lookahead index and jump to the step labelled process a ruby child.
If current annotations is not empty or if current annotation containers is not empty, then run the steps to commit a ruby segment.
If current child is an rb element, then run these substeps:
1. Run the steps to commit an automatic base.
2. If current bases is empty, then set current bases range start to the value of index.
3. Create a new DOM range whose start is the boundary point (root, index) and whose end is the boundary point (root, index plus one), and append it at the end of current bases.
4. Increment index by one and jump to the step labelled process a ruby child.
If current automatic base nodes is empty, set current automatic base range start to the value of index.
Append current child at the end of current automatic base nodes.
Increment index by one and jump to the step labelled process a ruby child.

When the steps above say to commit a ruby segment, it means to run the following steps at that point in the algorithm:

Run the steps to commit an automatic base.
If current bases, current annotations, and current annotation containers are all empty, abort these steps.
Run the steps to commit the base range.
Run the steps to commit current annotations.
Create a new ruby segment. It is described by a list of bases set to current bases, a base DOM range set to current bases range, and a list of ruby annotation containers that are the current annotation containers list. Append this new ruby segment at the end of ruby segments.
Let current bases be an empty list.
Let current bases range be null.
Let current bases range start be null.
Let current annotation containers be an empty list.

When the steps above say to commit the base range, it means to run the following steps at that point in the algorithm:

If current bases is empty, abort these steps.
If current bases range is not null, abort these steps.
Let current bases range be a DOM range whose start is the boundary point (root, current bases range start) and whose end is the boundary point (root, index).

When the steps above say to commit current annotations, it means to run the following steps at that point in the algorithm:

If current annotations is not empty and current annotations range is null let current annotations range be a DOM range whose start is the boundary point (root, current annotations range start) and whose end is the boundary point (root, index).
If current annotations is not empty, create a new ruby annotation container. It is described by an annotations list set to current annotations and a range set to current annotations range. Append this new ruby annotation container at the end of current annotation containers.
Let current annotations be an empty list of DOM ranges.
Let current annotations range be null.
Let current annotations range start be null.

When the steps above say to commit an automatic base, it means to run the following steps at that point in the algorithm:

If current automatic base nodes is empty, abort these steps.
If current automatic base nodes contains nodes that are not Text nodes, or Text nodes that are not inter-element whitespace, then run these substeps:
1. It current bases is empty, set current bases range start to the value of current automatic base range start.
2. Create a new DOM range whose start is the boundary point (root, current automatic base range start) and whose end is the boundary point (root, index), and append it at the end of current bases.
Let current automatic base nodes be an empty list of DOM Nodes.
Let current automatic base range start be null.

4.5.11 The `rb` element

Categories:: None.
Contexts in which this element can be used:: As a child of a ruby element.
Content model:: Phrasing content.
Content attributes:: Global attributes
Tag omission in text/html:: An rb element's end tag may be omitted if the rb element is immediately followed by an rb, rt, rtc or rp element, or if there is no more content in the parent element.
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The rb element marks the base text component of a ruby annotation. When it is the child of a ruby element, it doesn't represent anything itself, but its parent ruby element uses it as part of determining what it represents.

An rb element that is not a child of a ruby element represents the same thing as its children.

4.5.12 The `rt` element

Categories:: None.
Contexts in which this element can be used:: As a child of a ruby or of an rtc element.
Content model:: Phrasing content.
Content attributes:: Global attributes
Tag omission in text/html:: An rt element's end tag may be omitted if the rt element is immediately followed by an rb, rt, rtc or rp element, or if there is no more content in the parent element.
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The rt element marks the ruby text component of a ruby annotation. When it is the child of a ruby element or of an rtc element that is itself the child of a ruby element, it doesn't represent anything itself, but its ancestor ruby element uses it as part of determining what it represents.

An rt element that is not a child of a ruby element or of an rtc element that is itself the child of a ruby element represents the same thing as its children.

4.5.13 The `rtc` element

Categories:: None.
Contexts in which this element can be used:: As a child of a ruby element.
Content model:: Phrasing content, rt, or rp elements.
Content attributes:: Global attributes
Tag omission in text/html:: An rtc element's end tag may be omitted if the rtc element is immediately followed by an rb or rtc element, or if there is no more content in the parent element.
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The rtc element marks a ruby text container for ruby text components in a ruby annotation. When it is the child of a ruby element it doesn't represent anything itself, but its parent ruby element uses it as part of determining what it represents.

An rtc element that is not a child of a ruby element represents the same thing as its children.

When an rtc element is processed as part of the segmentation and categorisation of content for a ruby element, the following algorithm defines how to process an rtc element:

Let root be the rtc element for which the algorithm is being run.
Let index be 0.
Let annotations be an empty list of DOM ranges.
Let current automatic annotation nodes be an empty list of DOM nodes.
Let current automatic annotation range start be null.
Process an rtc child: If index is equal to or greater than the number of child nodes in root, then run the steps to commit an automatic annotation, return annotations, and abort these steps.
Let current child be the indexth node in root.
If current child is an rt element, then run these substeps:
1. Run the steps to commit an automatic annotation.
2. Create a new DOM range whose start is the boundary point (root, index) and whose end is the boundary point (root, index plus one), and append it at the end of annotations.
3. Increment index by one and jump to the step labelled process an rtc child.
If current automatic annotation nodes is empty, set current automatic annotation range start to the value of index.
Append current child at the end of current automatic annotation nodes.
Increment index by one and jump to the step labelled process an rtc child.

When the steps above say to commit an automatic annotation, it means to run the following steps at that point in the algorithm:

If current automatic annotation nodes is empty, abort these steps.
If current automatic annotation nodes contains nodes that are not Text nodes, or Text nodes that are not inter-element whitespace, then create a new DOM range whose start is the boundary point (root, current automatic annotation range start) and whose end is the boundary point (root, index), and append it at the end of annotations.
Let current automatic annotation nodes be an empty list of DOM nodes.
Let current automatic annotation range start be null.

4.5.14 The `rp` element

Categories:: None.
Contexts in which this element can be used:: As a child of a ruby or rtc element, either immediately before or immediately after an rt or rtc element, but not between rt elements.
Content model:: Phrasing content.
Content attributes:: Global attributes
Tag omission in text/html:: An rp element's end tag may be omitted if the rp element is immediately followed by an rb, rt, rtc or rp element, or if there is no more content in the parent element.
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The rp element is used to provide fallback text to be shown by user agents that don't support ruby annotations. One widespread convention is to provide parentheses around the ruby text component of a ruby annotation.

The contents of the rp elements are typically not displayed by user agents which do support ruby annotations

An rp element that is a child of a ruby element represents nothing. An rp element whose parent element is not a ruby element represents its children.

The example shown previously, in which each ideograph in the text 漢字 is annotated with its phonetic reading, could be expanded to use rp so that in legacy user agents the readings are in parentheses (please note that white space has been introduced into this example in order to make it more readable):

...
<ruby>
  漢
  <rb>字</rb>
  <rp> (</rp>
  <rt>かん</rt>
  <rt>じ</rt>
  <rp>) </rp>
</ruby>
...

In conforming user agents the rendering would be as above, but in user agents that do not support ruby, the rendering would be:

... 漢字 (かんじ) ...

When there are multiple annotations for a segment, rp elements can also be placed between the annotations. Here is another copy of an earlier contrived example showing some symbols with names given in English and French using double-sided annotations, but this time with rp elements as well:

<ruby>
  ♥<rp>: </rp><rt>Heart</rt><rp>, </rp><rtc><rt lang=fr>Cœur</rt></rtc><rp>.</rp>
  ☘<rp>: </rp><rt>Shamrock</rt><rp>, </rp><rtc><rt lang=fr>Trèfle</rt></rtc><rp>.</rp>
  ✶<rp>: </rp><rt>Star</rt><rp>, </rp><rtc><rt lang=fr>Étoile</rt></rtc><rp>.</rp>
</ruby>

This would make the example render as follows in non-ruby-capable user agents:

♥: Heart, Cœur.
☘: Shamrock, Trèfle.
✶: Star, Étoile.

4.5.15 The `data` element

Where phrasing content is expected.

Neither tag is omissible.

value — Machine-readable value

Allowed ARIA role attribute values:

Any aria-* attributes applicable to the allowed roles.

interface HTMLDataElement : HTMLElement {
  attribute DOMString value;
};

The data element represents its contents, along with a machine-readable form of those contents in the value attribute.

The value attribute must be present. Its value must be a representation of the element's contents in a machine-readable format.

When the value is date- or time-related, the more specific time element can be used instead.

The element can be used for several purposes.

When combined with microformats or the microdata attributes defined in this specification, the element serves to provide both a machine-readable value for the purposes of data processors, and a human-readable value for the purposes of rendering in a Web browser. In this case, the format to be used in the value attribute is determined by the microformats or microdata vocabulary in use.

The element can also, however, be used in conjunction with scripts in the page, for when a script has a literal value to store alongside a human-readable value. In such cases, the format to be used depends only on the needs of the script. (The data-* attributes can also be useful in such situations.)

The value IDL attribute must reflect the content attribute of the same name.

Here, a short table has its numeric values encoded using data so that the table sorting model can provide a sorting mechanism on each column, despite the numbers being presented in textual form in one column and in a decomposed form in another.

<table sortable>
 <thead> <tr> <th> Game <th> Corporations <th> Map Size
 <tbody>
  <tr> <td> 1830 <td> <data value="8">Eight</data> <td> <data value="93">19+74 hexes (93 total)</data>
  <tr> <td> 1856 <td> <data value="11">Eleven</data> <td> <data value="99">12+87 hexes (99 total)</data>
  <tr> <td> 1870 <td> <data value="10">Ten</data> <td> <data value="149">4+145 hexes (149 total)</data>
</table>

4.5.16 The `time` element

Where phrasing content is expected.

Neither tag is omissible.

datetime — Machine-readable value

Allowed ARIA role attribute values:

Any aria-* attributes applicable to the allowed roles.

A valid yearless date string

interface HTMLTimeElement : HTMLElement {
  attribute DOMString dateTime;
};

The time element represents its contents, along with a machine-readable form of those contents in the datetime attribute. The kind of content is limited to various kinds of dates, times, time-zone offsets, and durations, as described below.

The datetime attribute may be present. If present, its value must be a representation of the element's contents in a machine-readable format.

A time element that does not have a datetime content attribute must not have any element descendants.

The datetime value of a time element is the value of the element's datetime content attribute, if it has one, or the element's textContent, if it does not.

The datetime value of a time element must match one of the following syntaxes.

A valid month string

<time>2011-11</time>

A valid date string

<time>2011-11-18</time>

<time>11-18</time>

A valid time string

<time>14:54</time>

<time>14:54:39</time>

<time>14:54:39.929</time>

A valid local date and time string

<time>2011-11-18T14:54</time>

<time>2011-11-18T14:54:39</time>

<time>2011-11-18T14:54:39.929</time>

<time>2011-11-18 14:54</time>

<time>2011-11-18 14:54:39</time>

<time>2011-11-18 14:54:39.929</time>

Times with dates but without a time zone offset are useful for specifying events that are observed at the same specific time in each time zone, throughout a day. For example, the 2020 new year is celebrated at 2020-01-01 00:00 in each time zone, not at the same precise moment across all time zones. For events that occur at the same time across all time zones, for example a videoconference meeting, a valid global date and time string is likely more useful.

A valid time-zone offset string

<time>Z</time>

<time>+0000</time>

<time>+00:00</time>

<time>-0800</time>

<time>-08:00</time>

For times without dates (or times referring to events that recur on multiple dates), specifying the geographic location that controls the time is usually more useful than specifying a time zone offset, because geographic locations change time zone offsets with daylight savings time. In some cases, geographic locations even change time zone, e.g. when the boundaries of those time zones are redrawn, as happened with Samoa at the end of 2011. There exists a time zone database that describes the boundaries of time zones and what rules apply within each such zone, known as the time zone database. [TZDATABASE]

A valid global date and time string

<time>2011-11-18T14:54Z</time>

<time>2011-11-18T14:54:39Z</time>

<time>2011-11-18T14:54:39.929Z</time>

<time>2011-11-18T14:54+0000</time>

<time>2011-11-18T14:54:39+0000</time>

<time>2011-11-18T14:54:39.929+0000</time>

<time>2011-11-18T14:54+00:00</time>

<time>2011-11-18T14:54:39+00:00</time>

<time>2011-11-18T14:54:39.929+00:00</time>

<time>2011-11-18T06:54-0800</time>

<time>2011-11-18T06:54:39-0800</time>

<time>2011-11-18T06:54:39.929-0800</time>

<time>2011-11-18T06:54-08:00</time>

<time>2011-11-18T06:54:39-08:00</time>

<time>2011-11-18T06:54:39.929-08:00</time>

<time>2011-11-18 14:54Z</time>

<time>2011-11-18 14:54:39Z</time>

<time>2011-11-18 14:54:39.929Z</time>

<time>2011-11-18 14:54+0000</time>

<time>2011-11-18 14:54:39+0000</time>

<time>2011-11-18 14:54:39.929+0000</time>

<time>2011-11-18 14:54+00:00</time>

<time>2011-11-18 14:54:39+00:00</time>

<time>2011-11-18 14:54:39.929+00:00</time>

<time>2011-11-18 06:54-0800</time>

<time>2011-11-18 06:54:39-0800</time>

<time>2011-11-18 06:54:39.929-0800</time>

<time>2011-11-18 06:54-08:00</time>

<time>2011-11-18 06:54:39-08:00</time>

<time>2011-11-18 06:54:39.929-08:00</time>

Times with dates and a time zone offset are useful for specifying specific events, or recurring virtual events where the time is not anchored to a specific geographic location. For example, the precise time of an asteroid impact, or a particular meeting in a series of meetings held at 1400 UTC every day, regardless of whether any particular part of the world is observing daylight savings time or not. For events where the precise time varies by the local time zone offset of a specific geographic location, a valid local date and time string combined with that geographic location is likely more useful.

A valid week string

<time>2011-W47</time>

Four or more ASCII digits, at least one of which is not U+0030 DIGIT ZERO (0)

<time>2011</time>

<time>0001</time>

A valid duration string

<time>PT4H18M3S</time>

<time>4h 18m 3s</time>

The machine-readable equivalent of the element's contents must be obtained from the element's datetime value by using the following algorithm:

If parsing a month string from the element's datetime value returns a month, that is the machine-readable equivalent; abort these steps.
If parsing a date string from the element's datetime value returns a date, that is the machine-readable equivalent; abort these steps.
If parsing a yearless date string from the element's datetime value returns a yearless date, that is the machine-readable equivalent; abort these steps.
If parsing a time string from the element's datetime value returns a time, that is the machine-readable equivalent; abort these steps.
If parsing a local date and time string from the element's datetime value returns a local date and time, that is the machine-readable equivalent; abort these steps.
If parsing a time-zone offset string from the element's datetime value returns a time-zone offset, that is the machine-readable equivalent; abort these steps.
If parsing a global date and time string from the element's datetime value returns a global date and time, that is the machine-readable equivalent; abort these steps.
If parsing a week string from the element's datetime value returns a week, that is the machine-readable equivalent; abort these steps.
If the element's datetime value consists of only ASCII digits, at least one of which is not U+0030 DIGIT ZERO (0), then the machine-readable equivalent is the base-ten interpretation of those digits, representing a year; abort these steps.
If parsing a duration string from the element's datetime value returns a duration, that is the machine-readable equivalent; abort these steps.
There is no machine-readable equivalent.

The algorithms referenced above are intended to be designed such that for any arbitrary string s, only one of the algorithms returns a value. A more efficient approach might be to create a single algorithm that parses all these data types in one pass; developing such an algorithm is left as an exercise to the reader.

The dateTime IDL attribute must reflect the element's datetime content attribute.

The time element can be used to encode dates, for example in microformats. The following shows a hypothetical way of encoding an event using a variant on hCalendar that uses the time element:

<div class="vevent">
 <a class="url" href="http://www.web2con.com/">http://www.web2con.com/</a>
  <span class="summary">Web 2.0 Conference</span>:
  <time class="dtstart" datetime="2005-10-05">October 5</time> -
  <time class="dtend" datetime="2005-10-07">7</time>,
  at the <span class="location">Argent Hotel, San Francisco, CA</span>
 </div>

Here, a fictional microdata vocabulary based on the Atom vocabulary is used with the time element to mark up a blog post's publication date.

<article itemscope itemtype="http://n.example.org/rfc4287">
 <h1 itemprop="title">Big tasks</h1>
 <footer>Published <time itemprop="published" datetime="2009-08-29">two days ago</time>.</footer>
 <p itemprop="content">Today, I went out and bought a bike for my kid.</p>
</article>

In this example, another article's publication date is marked up using time, this time using the schema.org microdata vocabulary:

<article itemscope itemtype="http://schema.org/BlogPosting">
 <h1 itemprop="headline">Small tasks</h1>
 <footer>Published <time itemprop="datePublished" datetime="2009-08-30">yesterday</time>.</footer>
 <p itemprop="articleBody">I put a bike bell on his bike.</p>
</article>

In the following snippet, the time element is used to encode a date in the ISO8601 format, for later processing by a script:

<p>Our first date was <time datetime="2006-09-23">a Saturday</time>.</p>

In this second snippet, the value includes a time:

<p>We stopped talking at <time datetime="2006-09-24T05:00-07:00">5am the next morning</time>.</p>

A script loaded by the page (and thus privy to the page's internal convention of marking up dates and times using the time element) could scan through the page and look at all the time elements therein to create an index of dates and times.

For example, this element conveys the string "Tuesday" with the additional semantic that the 18th of November 2011 is the meaning that corresponds to "Tuesday":

Today is <time datetime="2011-11-18">Tuesday</time>.

In this example, a specific time in the Pacific Standard Time timezone is specified:

Your next meeting is at <time datetime="2011-11-18T15:00-08:00">3pm</time>.

4.5.17 The `code` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The code element represents a fragment of computer code. This could be an XML element name, a file name, a computer program, or any other string that a computer would recognize.

There is no formal way to indicate the language of computer code being marked up. Authors who wish to mark code elements with the language used, e.g. so that syntax highlighting scripts can use the right rules, can use the class attribute, e.g. by adding a class prefixed with "language-" to the element.

The following example shows how the element can be used in a paragraph to mark up element names and computer code, including punctuation.

<p>The <code>code</code> element represents a fragment of computer
code.</p>

<p>When you call the <code>activate()</code> method on the
<code>robotSnowman</code> object, the eyes glow.</p>

<p>The example below uses the <code>begin</code> keyword to indicate
the start of a statement block. It is paired with an <code>end</code>
keyword, which is followed by the <code>.</code> punctuation character
(full stop) to indicate the end of the program.</p>

The following example shows how a block of code could be marked up using the pre and code elements.

<pre><code class="language-pascal">var i: Integer;
begin
   i := 1;
end.</code></pre>

A class is used in that example to indicate the language used.

See the pre element for more details.

4.5.18 The `var` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The var element represents a variable. This could be an actual variable in a mathematical expression or programming context, an identifier representing a constant, a symbol identifying a physical quantity, a function parameter, or just be a term used as a placeholder in prose.

In the paragraph below, the letter "n" is being used as a variable in prose:

<p>If there are <var>n</var> pipes leading to the ice
cream factory then I expect at <em>least</em> <var>n</var>
flavors of ice cream to be available for purchase!</p>

For mathematics, in particular for anything beyond the simplest of expressions, MathML is more appropriate. However, the var element can still be used to refer to specific variables that are then mentioned in MathML expressions.

In this example, an equation is shown, with a legend that references the variables in the equation. The expression itself is marked up with MathML, but the variables are mentioned in the figure's legend using var.

<figure>
 <math>
  <mi>a</mi>
  <mo>=</mo>
  <msqrt>
   <msup><mi>b</mi><mn>2</mn></msup>
   <mi>+</mi>
   <msup><mi>c</mi><mn>2</mn></msup>
  </msqrt>
 </math>
 <figcaption>
  Using Pythagoras' theorem to solve for the hypotenuse <var>a</var> of
  a triangle with sides <var>b</var> and <var>c</var>
 </figcaption>
</figure>

Here, the equation describing mass-energy equivalence is used in a sentence, and the var element is used to mark the variables and constants in that equation:

<p>Then he turned to the blackboard and picked up the chalk. After a few moment's
thought, he wrote <var>E</var> = <var>m</var> <var>c</var><sup>2</sup>. The teacher
looked pleased.</p>

4.5.19 The `samp` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The samp element represents sample or quoted output from another program or computing system.

See the pre and kbd elements for more details.

This element can be contrasted with the output element, which can be used to provide immediate output in a Web application.

This example shows the samp element being used inline:

<p>The computer said <samp>Too much cheese in tray
two</samp> but I didn't know what that meant.</p>

This second example shows a block of sample output. Nested samp and kbd elements allow for the styling of specific elements of the sample output using a style sheet. There's also a few parts of the samp that are annotated with even more detailed markup, to enable very precise styling. To achieve this, span elements are used.

<pre><samp><span class="prompt">jdoe@mowmow:~$</span> <kbd>ssh demo.example.com</kbd>
Last login: Tue Apr 12 09:10:17 2005 from mowmow.example.com on pts/1
Linux demo 2.6.10-grsec+gg3+e+fhs6b+nfs+gr0501+++p3+c4a+gr2b-reslog-v6.189 #1 SMP Tue Feb 1 11:22:36 PST 2005 i686 unknown

<span class="prompt">jdoe@demo:~$</span> <span class="cursor">_</span></samp></pre>

4.5.20 The `kbd` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The kbd element represents user input (typically keyboard input, although it may also be used to represent other input, such as voice commands).

When the kbd element is nested inside a samp element, it represents the input as it was echoed by the system.

When the kbd element contains a samp element, it represents input based on system output, for example invoking a menu item.

When the kbd element is nested inside another kbd element, it represents an actual key or other single unit of input as appropriate for the input mechanism.

Here the kbd element is used to indicate keys to press:

<p>To make George eat an apple, press <kbd><kbd>Shift</kbd>+<kbd>F3</kbd></kbd></p>

In this second example, the user is told to pick a particular menu item. The outer kbd element marks up a block of input, with the inner kbd elements representing each individual step of the input, and the samp elements inside them indicating that the steps are input based on something being displayed by the system, in this case menu labels:

<p>To make George eat an apple, select
    <kbd><kbd><samp>File</samp></kbd>|<kbd><samp>Eat Apple...</samp></kbd></kbd>
</p>

Such precision isn't necessary; the following is equally fine:

<p>To make George eat an apple, select <kbd>File | Eat Apple...</kbd></p>

4.5.21 The `sub` and `sup` elements

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Use HTMLElement.

The sup element represents a superscript and the sub element represents a subscript.

These elements must be used only to mark up typographical conventions with specific meanings, not for typographical presentation for presentation's sake. For example, it would be inappropriate for the sub and sup elements to be used in the name of the LaTeX document preparation system. In general, authors should use these elements only if the absence of those elements would change the meaning of the content.

In certain languages, superscripts are part of the typographical conventions for some abbreviations.

<p>The most beautiful women are
<span lang="fr"><abbr>M<sup>lle</sup></abbr> Gwendoline</span> and
<span lang="fr"><abbr>M<sup>me</sup></abbr> Denise</span>.</p>

The sub element can be used inside a var element, for variables that have subscripts.

Here, the sub element is used to represent the subscript that identifies the variable in a family of variables:

<p>The coordinate of the <var>i</var>th point is
(<var>x<sub><var>i</var></sub></var>, <var>y<sub><var>i</var></sub></var>).
For example, the 10th point has coordinate
(<var>x<sub>10</sub></var>, <var>y<sub>10</sub></var>).</p>

Mathematical expressions often use subscripts and superscripts. Authors are encouraged to use MathML for marking up mathematics, but authors may opt to use sub and sup if detailed mathematical markup is not desired. [MATHML]

<var>E</var>=<var>m</var><var>c</var><sup>2</sup>

f(<var>x</var>, <var>n</var>) = log<sub>4</sub><var>x</var><sup><var>n</var></sup>

4.5.22 The `i` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The i element represents a span of text in an alternate voice or mood, or otherwise offset from the normal prose in a manner indicating a different quality of text, such as a taxonomic designation, a technical term, an idiomatic phrase from another language, transliteration, a thought, or a ship name in Western texts.

Terms in languages different from the main text should be annotated with lang attributes (or, in XML, lang attributes in the XML namespace).

The examples below show uses of the i element:

<p>The <i class="taxonomy">Felis silvestris catus</i> is cute.</p>
<p>The term <i>prose content</i> is defined above.</p>
<p>There is a certain <i lang="fr">je ne sais quoi</i> in the air.</p>

In the following example, a dream sequence is marked up using i elements.

<p>Raymond tried to sleep.</p>
<p><i>The ship sailed away on Thursday</i>, he
dreamt. <i>The ship had many people aboard, including a beautiful
princess called Carey. He watched her, day-in, day-out, hoping she
would notice him, but she never did.</i></p>
<p><i>Finally one night he picked up the courage to speak with
her—</i></p>
<p>Raymond woke with a start as the fire alarm rang out.</p>

Authors can use the class attribute on the i element to identify why the element is being used, so that if the style of a particular use (e.g. dream sequences as opposed to taxonomic terms) is to be changed at a later date, the author doesn't have to go through the entire document (or series of related documents) annotating each use.

Authors are encouraged to consider whether other elements might be more applicable than the i element, for instance the em element for marking up stress emphasis, or the dfn element to mark up the defining instance of a term.

Style sheets can be used to format i elements, just like any other element can be restyled. Thus, it is not the case that content in i elements will necessarily be italicized.

4.5.23 The `b` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The b element represents a span of text to which attention is being drawn for utilitarian purposes without conveying any extra importance and with no implication of an alternate voice or mood, such as key words in a document abstract, product names in a review, actionable words in interactive text-driven software, or an article lede.

The following example shows a use of the b element to highlight key words without marking them up as important:

<p>The <b>frobonitor</b> and <b>barbinator</b> components are fried.</p>

In the following example, objects in a text adventure are highlighted as being special by use of the b element.

<p>You enter a small room. Your <b>sword</b> glows
brighter. A <b>rat</b> scurries past the corner wall.</p>

Another case where the b element is appropriate is in marking up the lede (or lead) sentence or paragraph. The following example shows how a BBC article about kittens adopting a rabbit as their own could be marked up:

<article>
 <h2>Kittens 'adopted' by pet rabbit</h2>
 <p><b class="lede">Six abandoned kittens have found an
 unexpected new mother figure — a pet rabbit.</b></p>
 <p>Veterinary nurse Melanie Humble took the three-week-old
 kittens to her Aberdeen home.</p>
[...]

As with the i element, authors can use the class attribute on the b element to identify why the element is being used, so that if the style of a particular use is to be changed at a later date, the author doesn't have to go through annotating each use.

The b element should be used as a last resort when no other element is more appropriate. In particular, headings should use the h1 to h6 elements, stress emphasis should use the em element, importance should be denoted with the strong element, and text marked or highlighted should use the mark element.

The following would be incorrect usage:

<p><b>WARNING!</b> Do not frob the barbinator!</p>

In the previous example, the correct element to use would have been strong, not b.

Style sheets can be used to format b elements, just like any other element can be restyled. Thus, it is not the case that content in b elements will necessarily be boldened.

4.5.24 The `u` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The u element represents a span of text with an unarticulated, though explicitly rendered, non-textual annotation, such as labeling the text as being a proper name in Chinese text (a Chinese proper name mark), or labeling the text as being misspelt.

In most cases, another element is likely to be more appropriate: for marking stress emphasis, the em element should be used; for marking key words or phrases either the b element or the mark element should be used, depending on the context; for marking book titles, the cite element should be used; for labeling text with explicit textual annotations, the ruby element should be used; for labeling ship names in Western texts, the i element should be used.

The default rendering of the u element in visual presentations clashes with the conventional rendering of hyperlinks (underlining). Authors are encouraged to avoid using the u element where it could be confused for a hyperlink.

In this example, a u element is used to mark a word as misspelt:

<p>The <u>see</u> is full of fish.</p>

4.5.25 The `mark` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The mark element represents a run of text in one document marked or highlighted for reference purposes, due to its relevance in another context. When used in a quotation or other block of text referred to from the prose, it indicates a highlight that was not originally present but which has been added to bring the reader's attention to a part of the text that might not have been considered important by the original author when the block was originally written, but which is now under previously unexpected scrutiny. When used in the main prose of a document, it indicates a part of the document that has been highlighted due to its likely relevance to the user's current activity.

This example shows how the mark element can be used to bring attention to a particular part of a quotation:

<p lang="en-US">Consider the following quote:</p>
<blockquote lang="en-GB">
 <p>Look around and you will find, no-one's really
 <mark>colour</mark> blind.</p>
</blockquote>
<p lang="en-US">As we can tell from the <em>spelling</em> of the word,
the person writing this quote is clearly not American.</p>

(If the goal was to mark the element as misspelt, however, the u element, possibly with a class, would be more appropriate.)

Another example of the mark element is highlighting parts of a document that are matching some search string. If someone looked at a document, and the server knew that the user was searching for the word "kitten", then the server might return the document with one paragraph modified as follows:

<p>I also have some <mark>kitten</mark>s who are visiting me
these days. They're really cute. I think they like my garden! Maybe I
should adopt a <mark>kitten</mark>.</p>

In the following snippet, a paragraph of text refers to a specific part of a code fragment.

<p>The highlighted part below is where the error lies:</p>
<pre><code>var i: Integer;
begin
   i := <mark>1.1</mark>;
end.</code></pre>

This is separate from syntax highlighting, for which span is more appropriate. Combining both, one would get:

<p>The highlighted part below is where the error lies:</p>
<pre><code><span class=keyword>var</span> <span class=ident>i</span>: <span class=type>Integer</span>;
<span class=keyword>begin</span>
   <span class=ident>i</span> := <span class=literal><mark>1.1</mark></span>;
<span class=keyword>end</span>.</code></pre>

This is another example showing the use of mark to highlight a part of quoted text that was originally not emphasized. In this example, common typographic conventions have led the author to explicitly style mark elements in quotes to render in italics.

<article>
 <style scoped>
  blockquote mark, q mark {
    font: inherit; font-style: italic;
    text-decoration: none;
    background: transparent; color: inherit;
  }
  .bubble em {
    font: inherit; font-size: larger;
    text-decoration: underline;
  }
 </style>
 <h1>She knew</h1>
 <p>Did you notice the subtle joke in the joke on panel 4?</p>
 <blockquote>
  <p class="bubble">I didn't <em>want</em> to believe. <mark>Of course
  on some level I realised it was a known-plaintext attack.</mark> But I
  couldn't admit it until I saw for myself.</p>
 </blockquote>
 <p>(Emphasis mine.) I thought that was great. It's so pedantic, yet it
 explains everything neatly.</p>
</article>

Note, incidentally, the distinction between the em element in this example, which is part of the original text being quoted, and the mark element, which is highlighting a part for comment.

The following example shows the difference between denoting the importance of a span of text (strong) as opposed to denoting the relevance of a span of text (mark). It is an extract from a textbook, where the extract has had the parts relevant to the exam highlighted. The safety warnings, important though they may be, are apparently not relevant to the exam.

<h3>Wormhole Physics Introduction</h3>

<p><mark>A wormhole in normal conditions can be held open for a
maximum of just under 39 minutes.</mark> Conditions that can increase
the time include a powerful energy source coupled to one or both of
the gates connecting the wormhole, and a large gravity well (such as a
black hole).</p>

<p><mark>Momentum is preserved across the wormhole. Electromagnetic
radiation can travel in both directions through a wormhole,
but matter cannot.</mark></p>

<p>When a wormhole is created, a vortex normally forms.
<strong>Warning: The vortex caused by the wormhole opening will
annihilate anything in its path.</strong> Vortexes can be avoided when
using sufficiently advanced dialing technology.</p>

<p><mark>An obstruction in a gate will prevent it from accepting a
wormhole connection.</mark></p>

4.5.26 The `bdi` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes; Also, the dir global attribute has special semantics on this element.
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The bdi element represents a span of text that is to be isolated from its surroundings for the purposes of bidirectional text formatting. [BIDI]

The dir global attribute defaults to auto on this element (it never inherits from the parent element like with other elements).

This element has rendering requirements involving the bidirectional algorithm.

This element is especially useful when embedding user-generated content with an unknown directionality.

In this example, usernames are shown along with the number of posts that the user has submitted. If the bdi element were not used, the username of the Arabic user would end up confusing the text (the bidirectional algorithm would put the colon and the number "3" next to the word "User" rather than next to the word "posts").

<ul>
 <li>User <bdi>jcranmer</bdi>: 12 posts.
 <li>User <bdi>hober</bdi>: 5 posts.
 <li>User <bdi>إيان</bdi>: 3 posts.
</ul>

When using the `bdi` element, the username acts as expected.

If the `bdi` element were to be replaced by a `b` element, the username would confuse the bidirectional algorithm and the third bullet would end up saying "User 3 :", followed by the Arabic name (right-to-left), followed by "posts" and a period.

4.5.27 The `bdo` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Phrasing content.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes; Also, the dir global attribute has special semantics on this element.
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The bdo element represents explicit text directionality formatting control for its children. It allows authors to override the Unicode bidirectional algorithm by explicitly specifying a direction override. [BIDI]

Authors must specify the dir attribute on this element, with the value ltr to specify a left-to-right override and with the value rtl to specify a right-to-left override. The auto value must not be specified.

This element has rendering requirements involving the bidirectional algorithm.

4.5.28 The `span` element

Where phrasing content is expected.

Neither tag is omissible.

Allowed ARIA role attribute values:

Any aria-* attributes applicable to the allowed roles.

interface HTMLSpanElement : HTMLElement {};

The span element doesn't mean anything on its own, but can be useful when used together with the global attributes, e.g. class, lang, or dir. It represents its children.

In this example, a code fragment is marked up using span elements and class attributes so that its keywords and identifiers can be colour-coded from CSS:

<pre><code class="lang-c"><span class="keyword">for</span> (<span class="ident">j</span> = 0; <span class="ident">j</span> &lt; 256; <span class="ident">j</span>++) {
  <span class="ident">i_t3</span> = (<span class="ident">i_t3</span> & 0x1ffff) | (<span class="ident">j</span> &lt;&lt; 17);
  <span class="ident">i_t6</span> = (((((((<span class="ident">i_t3</span> >> 3) ^ <span class="ident">i_t3</span>) >> 1) ^ <span class="ident">i_t3</span>) >> 8) ^ <span class="ident">i_t3</span>) >> 5) & 0xff;
  <span class="keyword">if</span> (<span class="ident">i_t6</span> == <span class="ident">i_t1</span>)
    <span class="keyword">break</span>;
}</code></pre>

4.5.29 The `br` element

Where phrasing content is expected.

No end tag.

Allowed ARIA role attribute values:

Any aria-* attributes applicable to the allowed roles.

Viewport-based selection

interface HTMLBRElement : HTMLElement {
  // also has obsolete members
};

The br element represents a line break.

While line breaks are usually represented in visual media by physically moving subsequent text to a new line, a style sheet or user agent would be equally justified in causing line breaks to be rendered in a different manner, for instance as green dots, or as extra spacing.

br elements must be used only for line breaks that are actually part of the content, as in poems or addresses.

The following example is correct usage of the br element:

<p>P. Sherman<br>
42 Wallaby Way<br>
Sydney</p>

br elements must not be used for separating thematic groups in a paragraph.

The following examples are non-conforming, as they abuse the br element:

<p><a ...>34 comments.</a><br>
<a ...>Add a comment.</a></p>

<p><label>Name: <input name="name"></label><br>
<label>Address: <input name="address"></label></p>

Here are alternatives to the above, which are correct:

<p><a ...>34 comments.</a></p>
<p><a ...>Add a comment.</a></p>

<p><label>Name: <input name="name"></label></p>
<p><label>Address: <input name="address"></label></p>

If a paragraph consists of nothing but a single br element, it represents a placeholder blank line (e.g. as in a template). Such blank lines must not be used for presentation purposes.

Any content inside br elements must not be considered part of the surrounding text.

This element has rendering requirements involving the bidirectional algorithm.

4.5.30 The `wbr` element

Categories:: Flow content.; Phrasing content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Nothing.
Tag omission in text/html:: No end tag.
Content attributes:: Global attributes
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses HTMLElement.

The wbr element represents a line break opportunity.

In the following example, someone is quoted as saying something which, for effect, is written as one long word. However, to ensure that the text can be wrapped in a readable fashion, the individual words in the quote are separated using a wbr element.

<p>So then he pointed at the tiger and screamed
"there<wbr>is<wbr>no<wbr>way<wbr>you<wbr>are<wbr>ever<wbr>going<wbr>to<wbr>catch<wbr>me"!</p>

Here, especially long lines of code in a program listing have suggested wrapping points given using wbr elements.

<pre>...
Heading heading = Helm.HeadingFactory(HeadingCoordinates[1], <wbr>HeadingCoordinates[2], <wbr>HeadingCoordinates[3], <wbr>HeadingCoordinates[4]);
Course course = Helm.CourseFactory(Heading, <wbr>Maps.MapFactoryFromHeading(heading), <wbr>Speeds.GetMaximumSpeed().ConvertToWarp());
...</pre>

Any content inside wbr elements must not be considered part of the surrounding text.

var wbr = document.createElement("wbr");
wbr.textContent = "This is wrong";
document.body.appendChild(wbr);

This element has rendering requirements involving the bidirectional algorithm.

4.5.31 Usage summary

This section is non-normative.

Element	Purpose	Example
`a`	Hyperlinks	Visit my <a href="drinks.html">drinks</a> page.
`em`	Stress emphasis	I must say I <em>adore</em> lemonade.
`strong`	Importance	This tea is <strong>very hot</strong>.
`small`	Side comments	These grapes are made into wine. <small>Alcohol is addictive.</small>
`s`	Inaccurate text	Price: <s>£4.50</s> £2.00!
`cite`	Titles of works	The case <cite>Hugo v. Danielle</cite> is relevant here.
`q`	Quotations	The judge said <q>You can drink water from the fish tank</q> but advised against it.
`dfn`	Defining instance	The term <dfn>organic food</dfn> refers to food produced without synthetic chemicals.
`abbr`	Abbreviations	Organic food in Ireland is certified by the <abbr title="Irish Organic Farmers and Growers Association">IOFGA</abbr>.
`ruby`, `rb`, `rp`, `rt`, `rtc`	Ruby annotations	<ruby> <rb>OJ <rp>(<rtc><rt>Orange Juice</rtc><rp>)</ruby>
`data`	Machine-readable equivalent	Available starting today! <data value="UPC:022014640201">North Coast Organic Apple Cider</data>
`time`	Machine-readable equivalent of date- or time-related data	Available starting on <time datetime="2011-11-12">November 12th</time>!
`code`	Computer code	The <code>fruitdb</code> program can be used for tracking fruit production.
`var`	Variables	If there are <var>n</var> fruit in the bowl, at least <var>n</var>÷2 will be ripe.
`samp`	Computer output	The computer said <samp>Unknown error -3</samp>.
`kbd`	User input	Hit <kbd>F1</kbd> to continue.
`sub`	Subscripts	Water is H<sub>2</sub>O.
`sup`	Superscripts	The Hydrogen in heavy water is usually <sup>2</sup>H.
`i`	Alternative voice	Lemonade consists primarily of <i>Citrus limon</i>.
`b`	Keywords	Take a <b>lemon</b> and squeeze it with a <b>juicer</b>.
`u`	Annotations	The mixture of apple juice and <u class="spelling">eldeflower</u> juice is very pleasant.
`mark`	Highlight	Elderflower cordial, with one <mark>part</mark> cordial to ten <mark>part</mark>s water, stands a<mark>part</mark> from the rest.
`bdi`	Text directionality isolation	The recommended restaurant is <bdi lang="">My Juice Café (At The Beach)</bdi>.
`bdo`	Text directionality formatting	The proposal is to write English, but in reverse order. "Juice" would become "<bdo dir=rtl>Juice</bdo>"
`span`	Other	In French we call it <span lang="fr">sirop de sureau</span>.
`br`	Line break	Simply Orange Juice Company<br>Apopka, FL 32703<br>U.S.A.
`wbr`	Line breaking opportunity	www.simply<wbr>orange<wbr>juice.com

4.6 Links

4.6.1 Introduction

Links are a conceptual construct, created by a, area, and link elements, that represent a connection between two resources, one of which is the current Document. There are two kinds of links in HTML:

Links to external resources: These are links to resources that are to be used to augment the current document, generally automatically processed by the user agent.
Hyperlinks: These are links to other resources that are generally exposed to the user by the user agent so that the user can cause the user agent to navigate to those resources, e.g. to visit them in a browser or download them.

For link elements with an href attribute and a rel attribute, links must be created for the keywords of the rel attribute, as defined for those keywords in the link types section.

Similarly, for a and area elements with an href attribute and a rel attribute, links must be created for the keywords of the rel attribute as defined for those keywords in the link types section. Unlike link elements, however, a and area elements with an href attribute that either do not have a rel attribute, or whose rel attribute has no keywords that are defined as specifying hyperlinks, must also create a hyperlink. This implied hyperlink has no special meaning (it has no link type) beyond linking the element's node document to the resource given by the element's href attribute.

A hyperlink can have one or more hyperlink annotations that modify the processing semantics of that hyperlink.

4.6.2 Links created by `a` and `area` elements

The href attribute on a and area elements must have a value that is a valid URL potentially surrounded by spaces.

The href attribute on a and area elements is not required; when those elements do not have href attributes they do not create hyperlinks.

The target attribute, if present, must be a valid browsing context name or keyword. It gives the name of the browsing context that will be used. User agents use this name when following hyperlinks.

When an a or area element's activation behaviour is invoked, the user agent may allow the user to indicate a preference regarding whether the hyperlink is to be used for navigation or whether the resource it specifies is to be downloaded.

In the absence of a user preference, the default should be navigation if the element has no download attribute, and should be to download the specified resource if it does.

Whether determined by the user's preferences or via the presence or absence of the attribute, if the decision is to use the hyperlink for navigation then the user agent must follow the hyperlink, and if the decision is to use the hyperlink to download a resource, the user agent must download the hyperlink. These terms are defined in subsequent sections below.

The download attribute, if present, indicates that the author intends the hyperlink to be used for downloading a resource. The attribute may have a value; the value, if any, specifies the default file name that the author recommends for use in labeling the resource in a local file system. There are no restrictions on allowed values, but authors are cautioned that most file systems have limitations with regard to what punctuation is supported in file names, and user agents are likely to adjust file names accordingly.

The rel attribute on a and area elements controls what kinds of links the elements create. The attribute's value must be a set of space-separated tokens. The allowed keywords and their meanings are defined below.

The rel attribute has no default value. If the attribute is omitted or if none of the values in the attribute are recognised by the user agent, then the document has no particular relationship with the destination resource other than there being a hyperlink between the two.

The hreflang attribute on a and area elements that create hyperlinks, if present, gives the language of the linked resource. It is purely advisory. The value must be a valid BCP 47 language tag. [BCP47] User agents must not consider this attribute authoritative — upon fetching the resource, user agents must use only language information associated with the resource to determine its language, not metadata included in the link to the resource.

The type attribute, if present, gives the MIME type of the linked resource. It is purely advisory. The value must be a valid MIME type. User agents must not consider the type attribute authoritative — upon fetching the resource, user agents must not use metadata included in the link to the resource to determine its type.

4.6.3 API for `a` and `area` elements

[NoInterfaceObject, Exposed=Window]
interface HTMLHyperlinkElementUtils {
  stringifier attribute USVString href;
           attribute USVString origin;
           attribute USVString protocol;
           attribute USVString username;
           attribute USVString password;
           attribute USVString host;
           attribute USVString hostname;
           attribute USVString port;
           attribute USVString pathname;
           attribute USVString search;
           attribute USVString hash;
};

hyperlink . toString()

hyperlink . href

Returns the hyperlink's URL.

Can be set, to change the URL.

hyperlink . origin

Returns the hyperlink's URL's origin.

hyperlink . protocol

Returns the hyperlink's URL's scheme.

Can be set, to change the URL's scheme.

hyperlink . username

Returns the hyperlink's URL's username.

Can be set, to change the URL's username.

hyperlink . password

Returns the hyperlink's URL's password.

Can be set, to change the URL's password.

hyperlink . host

Returns the hyperlink's URL's host and port (if different from the default port for the scheme).

Can be set, to change the URL's host and port.

hyperlink . hostname

Returns the hyperlink's URL's host.

Can be set, to change the URL's host.

hyperlink . port

Returns the hyperlink's URL's port.

Can be set, to change the URL's port.

hyperlink . pathname

Returns the hyperlink's URL's path.

Can be set, to change the URL's path.

hyperlink . search

Returns the hyperlink's URL's query (includes leading "?" if non-empty).

Can be set, to change the URL's query (ignores leading "?").

hyperlink . hash

Returns the hyperlink's URL's fragment (includes leading "#" if non-empty).

Can be set, to change the URL's fragment (ignores leading "#").

An element implementing the HTMLHyperlinkElementUtils mixin has an associated url (null or a URL). It is initially null.

An element implementing the HTMLHyperlinkElementUtils mixin has an associated set the url algorithm, which sets this element's url to the resulting parsed URL of resolving this element's href content attribute value relative to this element. If resolving was aborted with an error, set this element's url to null.

When elements implementing the HTMLHyperlinkElementUtils mixin are created, and whenever those elements have their href content attribute set, changed, or removed, the user agent must set the url.

This is only observable for blob: URLs as parsing them involves the structured clone algorithm.

An element implementing the HTMLHyperlinkElementUtils mixin has an associated reinitialise url algorithm, which runs these steps:

If element's url is null or its non-relative flag is set, terminate these steps.
Set the url.

To update href, set the element's href content attribute's value to the element's url, serialised.

The href attribute's getter must run these steps:

Reinitialise url.
Let url be this element's url.
If url is null and this element has no href content attribute, return the empty string.
Otherwise, if url is null, return this element's href content attribute's value.
Return url, serialised.

The href attribute's setter must set this element's href content attribute's value to the given value.

The origin attribute's getter must run these steps:

Reinitialise url.
If this element's url is null, return the empty string.
Return the Unicode serialization of this element's url's origin.

It returns the Unicode rather than the ASCII serialisation for compatibility with MessageEvent.

The protocol attribute's getter must run these steps:

Reinitialise url.
If this element's url is null, return ":".
Return this element's url's scheme, followed by ":".

The protocol attribute's setter must run these steps:

Reinitialise url.
If this element's url is null, terminate these steps.
Basic URL parse the given value, followed by :", with this element's url as url and scheme start state as state override.
Update href.

The username attribute's getter must run these steps:

Reinitialise url.
If this element's url is null, return the empty string.
Return this element's url's username.

The username attribute's setter must run these steps:

Reinitialise url.
Let url be this element's url.
If url or url's host is null, or url's non-relative flag is set, terminate these steps.
Set the username, given url and the given value.
Update href.

The password attribute's getter must run these steps:

Reinitialise url.
Let url be this element's url.
If url or url's password is null, return the empty string.
Return url's password.

The password attribute's setter must run these steps:

Reinitialise url.
Let url be this element's url.
If url or url's host is null, or url's non-relative flag is set, terminate these steps.
Set the password, given url and the given value.
Update href.

The host attribute's getter must run these steps:

Reinitialise url.
Let url be this element's url.
If url or url's host is null, return the empty string.
If url's port is null, return url's host, serialised.
Return url's host, serialised, followed by ":" and url's port, serialised.

The host attribute's setter must run these steps:

Reinitialise url.
Let url be this element's url.
If url is null or url's non-relative flag is set, terminate these steps.
Basic URL parse the given value, with url as url and host state as state override.
Update href.

The hostname attribute's getter must run these steps:

Reinitialise url.
Let url be this element's url.
If url or url's host is null, return the empty string.
Return url's host, serialised.

The hostname attribute's setter must run these steps:

Reinitialise url.
Let url be this element's url.
If url is null or url's non-relative flag is set, terminate these steps.
Basic URL parse the given value, with url as url and hostname state as state override.
Update href.

The port attribute's getter must run these steps:

Reinitialise url.
Let url be this element's url.
If url or url's port is null, return the empty string.
Return url's port, serialised.

The port attribute's setter must run these steps:

Reinitialise url.
Let url be this element's url.
If url or url's host is null, url's non-relative flag is set, or url's scheme is "file", terminate these steps.
Basic URL parse the given value, with url as url and port state as state override.
Update href.

The pathname attribute's getter must run these steps:

Reinitialise url.
Let url be this element's url.
If url is null, return the empty string.
If url's non-relative flag is set, return the first string in url's path.
Return "/", followed by the strings in url's path (including empty strings), separated from each other by "/".

The pathname attribute's setter must run these steps:

Reinitialise url.
Let url be this element's url.
If url is null or url's non-relative flag is set, terminate these steps.
Set url's path to the empty list.
Basic URL parse the given value, with url as url and path start state as state override.
Update href.

The search attribute's getter must run these steps:

Reinitialise url.
Let url be this element's url.
If url is null, or url's query is either null or the empty string, return the empty string.
Return "?", followed by url's query.

The search attribute's setter must run these steps:

Reinitialise url.
Let url be this element's url.
If url is null, terminate these steps.
If the given value is the empty string, set url's query to null.
Otherwise, run these substeps:
1. Let input be the given value with a single leading "?" removed, if any.
2. Set url's query to the empty string.
3. Basic URL parse input, with url as url and query state as state override, and this element's node document's document's character encoding as encoding override.
Update href.

The hash attribute's getter must run these steps:

Reinitialise url.
Let url be this element's url.
If url is null, or url's fragment is either null or the empty string, return the empty string.
Return "#", followed by url's fragment.

The hash attribute's setter must run these steps:

Reinitialise url.
Let url be this element's url.
If url is null or url's scheme is "javascript", terminate these steps.
If the given value is the empty string, set url's fragment to null.
Otherwise, run these substeps:
1. Let input be the given value with a single leading "#" removed, if any.
2. Set url's fragment to the empty string.
3. Basic URL parse input, with url as url and fragment state as state override.
Update href.

4.6.4 Following hyperlinks

When a user follows a hyperlink created by an element subject, the user agent must run the following steps:

Let replace be false.
Let source be the browsing context that contains the Document object with which subject in question is associated.
If the user indicated a specific browsing context when following the hyperlink, or if the user agent is configured to follow hyperlinks by navigating a particular browsing context, then let target be that browsing context. If this is a new top-level browsing context (e.g. when the user followed the hyperlink using "Open in New Tab"), then source must be set as the new browsing context's one permitted sandboxed navigator.

Otherwise, if subject is an a or area element that has a target attribute, then let target be the browsing context that is chosen by applying the rules for choosing a browsing context given a browsing context name, using the value of the target attribute as the browsing context name. If these rules result in the creation of a new browsing context, set replace to true.

Otherwise, if target is an a or area element with no target attribute, but the Document contains a base element with a target attribute, then let target be the browsing context that is chosen by applying the rules for choosing a browsing context given a browsing context name, using the value of the target attribute of the first such base element as the browsing context name. If these rules result in the creation of a new browsing context, set replace to true.

Otherwise, let target be the browsing context that subject itself is in.
Resolve the URL given by the href attribute of that element, relative to that element.
If that is successful, let URL be the resulting absolute URL.

Otherwise, if resolving the URL failed, the user agent may report the error to the user in a user-agent-specific manner, may queue a task to navigate the target browsing context to an error page to report the error, or may ignore the error and do nothing. In any case, the user agent must then abort these steps.
In the case of server-side image maps, append the hyperlink suffix to URL.
Queue a task to navigate the target browsing context to URL. If replace is true, the navigation must be performed with replacement enabled. The source browsing context must be source.

The task source for the tasks mentioned above is the DOM manipulation task source.

4.6.5 Downloading resources

In some cases, resources are intended for later use rather than immediate viewing. To indicate that a resource is intended to be downloaded for use later, rather than immediately used, the download attribute can be specified on the a or area element that creates the hyperlink to that resource.

The attribute can furthermore be given a value, to specify the file name that user agents are to use when storing the resource in a file system. This value can be overridden by the `Content-Disposition` HTTP header's filename parameters. [RFC6266]

In cross-origin situations, the download attribute has to be combined with the `Content-Disposition` HTTP header, specifically with the attachment disposition type, to avoid the user being warned of possibly nefarious activity. (This is to protect users from being made to download sensitive personal or confidential information without their full understanding.)

When a user downloads a hyperlink created by an element, the user agent must run the following steps:

Resolve the URL given by the href attribute of that element, relative to that element.
If resolving the URL fails, the user agent may report the error to the user in a user-agent-specific manner, may navigate to an error page to report the error, or may ignore the error and do nothing. In either case, the user agent must abort these steps.
Otherwise, let URL be the resulting absolute URL.
In the case of server-side image maps, append the hyperlink suffix to URL.
Return to whatever algorithm invoked these steps and continue these steps in parallel.
Let request be a new request whose url is URL, client is entry settings object, initiator is "download", destination is the empty string, and whose omit-Origin-header flag, synchronous flag, and use-URL-credentials flag are all set.
Handle the result of fetching request as a download.

When a user agent is to handle a resource obtained from a fetch as a download, it should provide the user with a way to save the resource for later use, if a resource is successfully obtained; or otherwise should report any problems downloading the file to the user.

If the user agent needs a file name for a resource being handled as a download, it should select one using the following algorithm.

This algorithm is intended to mitigate security dangers involved in downloading files from untrusted sites, and user agents are strongly urged to follow it.

Let filename be the void value.
If the resource has a `Content-Disposition` header, that header specifies the attachment disposition type, and the header includes file name information, then let filename have the value specified by the header, and jump to the step labeled sanitize below. [RFC6266]
Let interface origin be the origin of the Document in which the download or navigate action resulting in the download was initiated, if any.
Let resource origin be the origin of the URL of the resource being downloaded, unless that URL's scheme component is data, in which case let resource origin be the same as the interface origin, if any.
If there is no interface origin, then let trusted operation be true. Otherwise, let trusted operation be true if resource origin is the same origin as interface origin, and false otherwise.
If trusted operation is true and the resource has a `Content-Disposition` header and that header includes file name information, then let filename have the value specified by the header, and jump to the step labeled sanitize below. [RFC6266]
If the download was not initiated from a hyperlink created by an a or area element, or if the element of the hyperlink from which it was initiated did not have a download attribute when the download was initiated, or if there was such an attribute but its value when the download was initiated was the empty string, then jump to the step labeled no proposed file name.
Let proposed filename have the value of the download attribute of the element of the hyperlink that initiated the download at the time the download was initiated.
If trusted operation is true, let filename have the value of proposed filename, and jump to the step labeled sanitize below.
If the resource has a `Content-Disposition` header and that header specifies the attachment disposition type, let filename have the value of proposed filename, and jump to the step labeled sanitize below. [RFC6266]
No proposed file name: If trusted operation is true, or if the user indicated a preference for having the resource in question downloaded, let filename have a value derived from the URL of the resource in a user-agent-defined manner, and jump to the step labeled sanitize below.
Act in a user-agent-defined manner to safeguard the user from a potentially hostile cross-origin download. If the download is not to be aborted, then let filename be set to the user's preferred file name or to a file name selected by the user agent, and jump to the step labeled sanitize below.

If the algorithm reaches this step, then a download was begun from a different origin than the resource being downloaded, and the origin did not mark the file as suitable for downloading, and the download was not initiated by the user. This could be because a download attribute was used to trigger the download, or because the resource in question is not of a type that the user agent supports.

This could be dangerous, because, for instance, a hostile server could be trying to get a user to unknowingly download private information and then re-upload it to the hostile server, by tricking the user into thinking the data is from the hostile server.

Thus, it is in the user's interests that the user be somehow notified that the resource in question comes from quite a different source, and to prevent confusion, any suggested file name from the potentially hostile interface origin should be ignored.
Sanitize: Optionally, allow the user to influence filename. For example, a user agent could prompt the user for a file name, potentially providing the value of filename as determined above as a default value.
Adjust filename to be suitable for the local file system.

For example, this could involve removing characters that are not legal in file names, or trimming leading and trailing whitespace.
If the platform conventions do not in any way use extensions to determine the types of file on the file system, then return filename as the file name and abort these steps.
Let claimed type be the type given by the resource's Content-Type metadata, if any is known. Let named type be the type given by filename's extension, if any is known. For the purposes of this step, a type is a mapping of a MIME type to an extension.
If named type is consistent with the user's preferences (e.g. because the value of filename was determined by prompting the user), then return filename as the file name and abort these steps.
If claimed type and named type are the same type (i.e. the type given by the resource's Content-Type metadata is consistent with the type given by filename's extension), then return filename as the file name and abort these steps.
If the claimed type is known, then alter filename to add an extension corresponding to claimed type.

Otherwise, if named type is known to be potentially dangerous (e.g. it will be treated by the platform conventions as a native executable, shell script, HTML application, or executable-macro-capable document) then optionally alter filename to add a known-safe extension (e.g. ".txt").

This last step would make it impossible to download executables, which might not be desirable. As always, implementors are forced to balance security and usability in this matter.
Return filename as the file name.

For the purposes of this algorithm, a file extension consists of any part of the file name that platform conventions dictate will be used for identifying the type of the file. For example, many operating systems use the part of the file name following the last dot (".") in the file name to determine the type of the file, and from that the manner in which the file is to be opened or executed.

User agents should ignore any directory or path information provided by the resource itself, its URL, and any download attribute, in deciding where to store the resulting file in the user's file system.

4.6.6 Link types

The following table summarizes the link types that are defined by this specification. This table is non-normative; the actual definitions for the link types are given in the next few sections.

In this section, the term referenced document refers to the resource identified by the element representing the link, and the term current document refers to the resource within which the element representing the link finds itself.

To determine which link types apply to a link, a, or area element, the element's rel attribute must be split on spaces. The resulting tokens are the link types that apply to that element.

Except where otherwise specified, a keyword must not be specified more than once per rel attribute.

Link types are always ASCII case-insensitive, and must be compared as such.

Thus, rel="next" is the same as rel="NEXT".

Link type	Effect on...		Brief description
Link type	`link`	`a` and `area`	Brief description
`alternate`	Hyperlink	Hyperlink	Gives alternate representations of the current document.
`author`	Hyperlink	Hyperlink	Gives a link to the author of the current document or article.
`bookmark`	not allowed	Hyperlink	Gives the permalink for the nearest ancestor section.
`help`	Hyperlink	Hyperlink	Provides a link to context-sensitive help.
`icon`	External Resource	not allowed	Imports an icon to represent the current document.
`license`	Hyperlink	Hyperlink	Indicates that the main content of the current document is covered by the copyright license described by the referenced document.
`next`	Hyperlink	Hyperlink	Indicates that the current document is a part of a series, and that the next document in the series is the referenced document.
`nofollow`	not allowed	Annotation	Indicates that the current document's original author or publisher does not endorse the referenced document.
`noreferrer`	not allowed	Annotation	Requires that the user agent not send an HTTP ``Referer`` (sic) header if the user follows the hyperlink.
`prefetch`	External Resource	External Resource	Specifies that the target resource should be preemptively cached.
`prev`	Hyperlink	Hyperlink	Indicates that the current document is a part of a series, and that the previous document in the series is the referenced document.
`search`	Hyperlink	Hyperlink	Gives a link to a resource that can be used to search through the current document and its related pages.
`stylesheet`	External Resource	not allowed	Imports a stylesheet.
`tag`	not allowed	Hyperlink	Gives a tag (identified by the given address) that applies to the current document.

Some of the types described below list synonyms for these values. These are to be handled as specified by user agents, but must not be used in documents.

4.6.6.1 Link type "`alternate`"

The alternate keyword may be used with link, a, and area elements.

The meaning of this keyword depends on the values of the other attributes.

If the element is a link element and the rel attribute also contains the keyword stylesheet

The alternate keyword modifies the meaning of the stylesheet keyword in the way described for that keyword. The alternate keyword does not create a link of its own.

If the alternate keyword is used with the type attribute set to the value application/rss+xml or the value application/atom+xml

The keyword creates a hyperlink referencing a syndication feed (though not necessarily syndicating exactly the same content as the current page).

The first link, a, or area element in the document (in tree order) with the alternate keyword used with the type attribute set to the value application/rss+xml or the value application/atom+xml must be treated as the default syndication feed for the purposes of feed autodiscovery.

The following link element gives the syndication feed for the current page:

<link rel="alternate" type="application/atom+xml" href="data.xml">

The following extract offers various different syndication feeds:

<p>You can access the planets database using Atom feeds:</p>
<ul>
 <li><a href="recently-visited-planets.xml" rel="alternate" type="application/atom+xml">Recently Visited Planets</a></li>
 <li><a href="known-bad-planets.xml" rel="alternate" type="application/atom+xml">Known Bad Planets</a></li>
 <li><a href="unexplored-planets.xml" rel="alternate" type="application/atom+xml">Unexplored Planets</a></li>
</ul>

Otherwise

The keyword creates a hyperlink referencing an alternate representation of the current document.

The nature of the referenced document is given by the hreflang, and type attributes.

If the alternate keyword is used with the hreflang attribute, and that attribute's value differs from the root element's language, it indicates that the referenced document is a translation.

If the alternate keyword is used with the type attribute, it indicates that the referenced document is a reformulation of the current document in the specified format.

The hreflang and type attributes can be combined when specified with the alternate keyword.

For example, the following link is a French translation that uses the PDF format:

<link rel=alternate type=application/pdf hreflang=fr href=manual-fr>

This relationship is transitive — that is, if a document links to two other documents with the link type "alternate", then, in addition to implying that those documents are alternative representations of the first document, it is also implying that those two documents are alternative representations of each other.

4.6.6.2 Link type "`author`"

The author keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

For a and area elements, the author keyword indicates that the referenced document provides further information about the author of the nearest article element ancestor of the element defining the hyperlink, if there is one, or of the page as a whole, otherwise.

For link elements, the author keyword indicates that the referenced document provides further information about the author for the page as a whole.

The "referenced document" can be, and often is, a mailto: URL giving the e-mail address of the author. [MAILTO]

Synonyms: For historical reasons, user agents must also treat link, a, and area elements that have a rev attribute with the value "made" as having the author keyword specified as a link relationship.

4.6.6.3 Link type "`bookmark`"

The bookmark keyword may be used with a and area elements. This keyword creates a hyperlink.

The bookmark keyword gives a permalink for the nearest ancestor article element of the linking element in question, or of the section the linking element is most closely associated with, if there are no ancestor article elements.

The following snippet has three permalinks. A user agent could determine which permalink applies to which part of the spec by looking at where the permalinks are given.

 ...
 <body>
  <h1>Example of permalinks</h1>
  <div id="a">
   <h2>First example</h2>
   <p><a href="a.html" rel="bookmark">This permalink applies to
   only the content from the first H2 to the second H2</a>. The DIV isn't
   exactly that section, but it roughly corresponds to it.</p>
  </div>
  <h2>Second example</h2>
  <article id="b">
   <p><a href="b.html" rel="bookmark">This permalink applies to
   the outer ARTICLE element</a> (which could be, e.g., a blog post).</p>
   <article id="c">
    <p><a href="c.html" rel="bookmark">This permalink applies to
    the inner ARTICLE element</a> (which could be, e.g., a blog comment).</p>
   </article>
  </article>
 </body>
 ...

4.6.6.4 Link type "`help`"

The help keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

For a and area elements, the help keyword indicates that the referenced document provides further help information for the parent of the element defining the hyperlink, and its children.

In the following example, the form control has associated context-sensitive help. The user agent could use this information, for example, displaying the referenced document if the user presses the "Help" or "F1" key.

 <p><label> Topic: <input name=topic> <a href="help/topic.html" rel="help">(Help)</a></label></p>

For link elements, the help keyword indicates that the referenced document provides help for the page as a whole.

For a and area elements, on some browsers, the help keyword causes the link to use a different cursor.

4.6.6.5 Link type "`icon`"

The icon keyword may be used with link elements. This keyword creates an external resource link.

The specified resource is an icon representing the page or site, and should be used by the user agent when representing the page in the user interface.

Icons could be auditory icons, visual icons, or other kinds of icons. If multiple icons are provided, the user agent must select the most appropriate icon according to the type, media, and sizes attributes. If there are multiple equally appropriate icons, user agents must use the last one declared in tree order at the time that the user agent collected the list of icons. If the user agent tries to use an icon but that icon is determined, upon closer examination, to in fact be inappropriate (e.g. because it uses an unsupported format), then the user agent must try the next-most-appropriate icon as determined by the attributes.

User agents are not required to update icons when the list of icons changes, but are encouraged to do so.

There is no default type for resources given by the icon keyword. However, for the purposes of determining the type of the resource, user agents must expect the resource to be an image.

The sizes attribute gives the sizes of icons for visual media. Its value, if present, is merely advisory. User agents may use the value to decide which icon(s) to use if multiple icons are available.

If specified, the attribute must have a value that is an unordered set of unique space-separated tokens which are ASCII case-insensitive. Each value must be either an ASCII case-insensitive match for the string "any", or a value that consists of two valid non-negative integers that do not have a leading U+0030 DIGIT ZERO (0) character and that are separated by a single U+0078 LATIN SMALL LETTER X or U+0058 LATIN CAPITAL LETTER X character.

The keywords represent icon sizes in raw pixels (as opposed to CSS pixels).

An icon that is 50 CSS pixels wide intended for displays with a device pixel density of two device pixels per CSS pixel (2x, 192dpi) would have a width of 100 raw pixels. This feature does not support indicating that a different resource is to be used for small high-resolution icons vs large low-resolution icons (e.g. 50×50 2x vs 100×100 1x).

To parse and process the attribute's value, the user agent must first split the attribute's value on spaces, and must then parse each resulting keyword to determine what it represents.

The any keyword represents that the resource contains a scalable icon, e.g. as provided by an SVG image.

Other keywords must be further parsed as follows to determine what they represent:

If the keyword doesn't contain exactly one U+0078 LATIN SMALL LETTER X or U+0058 LATIN CAPITAL LETTER X character, then this keyword doesn't represent anything. Abort these steps for that keyword.
Let width string be the string before the "x" or "X".
Let height string be the string after the "x" or "X".
If either width string or height string start with a U+0030 DIGIT ZERO (0) character or contain any characters other than ASCII digits, then this keyword doesn't represent anything. Abort these steps for that keyword.
Apply the rules for parsing non-negative integers to width string to obtain width.
Apply the rules for parsing non-negative integers to height string to obtain height.
The keyword represents that the resource contains a bitmap icon with a width of width device pixels and a height of height device pixels.

The keywords specified on the sizes attribute must not represent icon sizes that are not actually available in the linked resource.

In the absence of a link with the icon keyword, for Document objects obtained over HTTP or HTTPS, user agents may instead run these steps in parallel:

Let request be a new request whose url is the absolute URL obtained by resolving the URL "/favicon.ico" against the document's address, client is the Document object's Window object's environment settings object, type is "image", destination is "subresource", synchronous flag is set, credentials mode is "include", and whose use-URL-credentials flag is set.
Let response be the result of fetching request.
Use response's unsafe response as an icon as if it had been declared using the icon keyword.

The following snippet shows the top part of an application with several icons.

<!DOCTYPE HTML>
<html>
 <head>
  <title>lsForums — Inbox</title>
  <link rel=icon href=favicon.png sizes="16x16" type="image/png">
  <link rel=icon href=windows.ico sizes="32x32 48x48" type="image/vnd.microsoft.icon">
  <link rel=icon href=mac.icns sizes="128x128 512x512 8192x8192 32768x32768">
  <link rel=icon href=iphone.png sizes="57x57" type="image/png">
  <link rel=icon href=gnome.svg sizes="any" type="image/svg+xml">
  <link rel=stylesheet href=lsforums.css>
  <script src=lsforums.js></script>
  <meta name=application-name content="lsForums">
 </head>
 <body>
  ...

For historical reasons, the icon keyword may be preceded by the keyword "shortcut". If the "shortcut" keyword is present, the rel attribute's entire value must be an ASCII case-insensitive match for the string "shortcut icon" (with a single U+0020 SPACE character between the tokens and no other space characters).

4.6.6.6 Link type "`license`"

The license keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

The license keyword indicates that the referenced document provides the copyright license terms under which the main content of the current document is provided.

This specification defines the main content of a document and content that is not deemed to be part of that main content via the main element. The distinction should be made clear to the user.

Consider a photo sharing site. A page on that site might describe and show a photograph, and the page might be marked up as follows:

<!DOCTYPE HTML>
<html lang="en">
 <head>
  <title>Exampl Pictures: Kissat</title>
  <link rel="stylesheet" href="/style/default">
 </head>
 <body>
  <h1>Kissat</h1>
  <nav>
   <a href="../">Return to photo index</a>
  </nav>
  
  <main>
  <figure>
   <img src="/pix/39627052_fd8dcd98b5.jpg">
   <figcaption>Kissat</figcaption>
  </figure>
  <p>One of them has six toes!</p>
  <p><small>This photograph is <a rel="license" href="http://www.opensource.org/licenses/mit-license.php">MIT Licensed</a></small></p>
  </main>
  <footer>
   <a href="/">Home</a> | <a href="../">Photo index</a>
   <p><small>© copyright 2009 Exampl Pictures. All Rights Reserved.</small></p>
  </footer>
 </body>
</html>

In this case the license applies to just the photo (the main content of the document), not the whole document. In particular not the design of the page itself, which is covered by the copyright given at the bottom of the document. This should be made clear in the text referencing the licensing link and could also be made clearer in the styling (e.g. making the license link prominently positioned near the photograph, while having the page copyright in small text at the foot of the page, or adding a border to the main element.)

Synonyms: For historical reasons, user agents must also treat the keyword "copyright" like the license keyword.

4.6.6.7 Link type "`nofollow`"

The nofollow keyword may be used with a and area elements. This keyword does not create a hyperlink, but annotates any other hyperlinks created by the element (the implied hyperlink, if no other keywords create one).

The nofollow keyword indicates that the link is not endorsed by the original author or publisher of the page, or that the link to the referenced document was included primarily because of a commercial relationship between people affiliated with the two pages.

4.6.6.8 Link type "`noreferrer`"

The noreferrer keyword may be used with a and area elements. This keyword does not create a hyperlink, but annotates any other hyperlinks created by the element (the implied hyperlink, if no other keywords create one).

It indicates that no referrer information is to be leaked when following the link.

If a user agent follows a link defined by an a or area element that has the noreferrer keyword, the user agent must set their request's referrer to "no-referrer".

This keyword also causes the opener attribute to remain null if the hyperlink creates a new browsing context.

4.6.6.9 Link type "`prefetch`"

The prefetch keyword may be used with link, a, and area elements. This keyword creates an external resource link.

The prefetch keyword indicates that preemptively fetching and caching the specified resource is likely to be beneficial, as it is highly likely that the user will require this resource.

There is no default type for resources given by the prefetch keyword.

4.6.6.10 Link type "`search`"

The search keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

The search keyword indicates that the referenced document provides an interface specifically for searching the document and its related resources.

OpenSearch description documents can be used with link elements and the search link type to enable user agents to autodiscover search interfaces. [OPENSEARCH]

4.6.6.11 Link type "`stylesheet`"

The stylesheet keyword may be used with link elements. This keyword creates an external resource link that contributes to the styling processing model.

The specified resource is a resource that describes how to present the document. Exactly how the resource is to be processed depends on the actual type of the resource.

If the alternate keyword is also specified on the link element, then the link is an alternative stylesheet; in this case, the title attribute must be specified on the link element, with a non-empty value.

The default type for resources given by the stylesheet keyword is text/css.

The appropriate times to obtain the resource are:

When the external resource link is created on a link element that is already in a Document.
When the external resource link's link element is inserted into a document.
When the href attribute of the link element of an external resource link that is already in a Document is changed.
When the crossorigin attribute of the link element of an external resource link that is already in a Document is set, changed, or removed.
When the type attribute of the link element of an external resource link that is already in a Document is set or changed to a value that does not or no longer matches the Content-Type metadata of the previous obtained external resource, if any.
When the type attribute of the link element of an external resource link that is already in a Document but was previously not obtained due to the type attribute specifying an unsupported type is set, removed, or changed.
When the external resource link changes from being an alternative stylesheet to not being one, or vice versa.

Quirk: If the document has been set to quirks mode, has the same origin as the URL of the external resource, and the Content-Type metadata of the external resource is not a supported style sheet type, the user agent must instead assume it to be text/css.

Once a resource has been obtained, if its Content-Type metadata is text/css, the user agent must run these steps:

Let element be the link element that created the external resource link.
If element has an associated CSS style sheet, remove the CSS style sheet in question.
If element no longer creates an external resource link that contributes to the styling processing model, or if, since the resource in question was obtained, it has become appropriate to obtain it again (meaning this algorithm is about to be invoked again for a newly obtained resource), then abort these steps.
Create a CSS style sheet with the following properties:

type
text/css
location

The resulting absolute URL determined during the obtain algorithm.

This is before any redirects get applied.

owner node
element
media

The media attribute of element.

This is a reference to the (possibly absent at this time) attribute, rather than a copy of the attribute's current value. The CSSOM specification defines what happens when the attribute is dynamically set, changed, or removed.

title

The title attribute of element.

This is similarly a reference to the attribute, rather than a copy of the attribute's current value.

alternate flag
Set if the link is an alternative stylesheet; unset otherwise.
origin-clean flag
Set if the resource is CORS-same-origin; unset otherwise.
parent CSS style sheet
owner CSS rule
null
disabled flag
Left at its default value.
CSS rules
Left uninitialised.

The CSS environment encoding is the result of running the following steps: [CSSSYNTAX]
1. If the element has a charset attribute, get an encoding from that attribute's value. If that succeeds, return the resulting encoding and abort these steps. [ENCODING]
2. Otherwise, return the document's character encoding. [DOM]

4.6.6.12 Link type "`tag`"

The tag keyword may be used with a and area elements. This keyword creates a hyperlink.

The tag keyword indicates that the tag that the referenced document represents applies to the current document.

Since it indicates that the tag applies to the current document, it would be inappropriate to use this keyword in the markup of a tag cloud, which lists the popular tags across a set of pages.

This document is about some gems, and so it is tagged with "https://en.wikipedia.org/wiki/Gemstone" to unambiguously categorise it as applying to the "jewel" kind of gems, and not to, say, the towns in the US, the Ruby package format, or the Swiss locomotive class:

<!DOCTYPE HTML>
<html>
 <head>
  <title>My Precious</title>
 </head>
 <body>
  <header><h1>My precious</h1> <p>Summer 2012</p></header>
  <p>Recently I managed to dispose of a red gem that had been
  bothering me. I now have a much nicer blue sapphire.</p>
  <p>The red gem had been found in a bauxite stone while I was digging
  out the office level, but nobody was willing to haul it away. The
  same red gem stayed there for literally years.</p>
  <footer>
   Tags: <a rel=tag href="https://en.wikipedia.org/wiki/Gemstone">Gemstone</a>
  </footer>
 </body>
</html>

In this document, there are two articles. The "tag" link, however, applies to the whole page (and would do so wherever it was placed, including if it was within the article elements).

<!DOCTYPE HTML>
<html>
 <head>
  <title>Gem 4/4</title>
 </head>
 <body>
  <article>
   <h1>801: Steinbock</h1>
   <p>The number 801 Gem 4/4 electro-diesel has an ibex and was rebuilt in 2002.</p>
  </article>
  <article>
   <h1>802: Murmeltier</h1>
   <figure>
    <img src="https://upload.wikimedia.org/wikipedia/commons/b/b0/Trains_de_la_Bernina_en_hiver_2.jpg"
         alt="The 802 was red with pantographs and tall vents on the side.">
    <figcaption>The 802 in the 1980s, above Lago Bianco.</figcaption>
   </figure>
   <p>The number 802 Gem 4/4 electro-diesel has a marmot and was rebuilt in 2003.</p>
  </article>
  <p class="topic"><a rel=tag href="https://en.wikipedia.org/wiki/Rhaetian_Railway_Gem_4/4">Gem 4/4</a></p>
 </body>
</html>

4.6.6.13 Sequential link types

Some documents form part of a sequence of documents.

A sequence of documents is one where each document can have a previous sibling and a next sibling. A document with no previous sibling is the start of its sequence, a document with no next sibling is the end of its sequence.

A document may be part of multiple sequences.

4.6.6.13.1 Link type "`next`"

The next keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

The next keyword indicates that the document is part of a sequence, and that the link is leading to the document that is the next logical document in the sequence.

4.6.6.13.2 Link type "`prev`"

The prev keyword may be used with link, a, and area elements. This keyword creates a hyperlink.

The prev keyword indicates that the document is part of a sequence, and that the link is leading to the document that is the previous logical document in the sequence.

Synonyms: For historical reasons, user agents must also treat the keyword "previous" like the prev keyword.

4.6.6.14 Other link types

Extensions to the predefined set of link types may be registered in the microformats wiki existing-rel-values page. [MFREL]

Anyone is free to edit the microformats wiki existing-rel-values page at any time to add a type. Extension types must be specified with the following information:

Keyword

The actual value being defined. The value should not be confusingly similar to any other defined value (e.g. differing only in case).

If the value contains a U+003A COLON character (:), it must also be an absolute URL.

Effect on... link

One of the following:

Not allowed: The keyword must not be specified on link elements.
Hyperlink: The keyword may be specified on a link element; it creates a hyperlink.
External Resource: The keyword may be specified on a link element; it creates an external resource link.

Effect on... a and area

One of the following:

Not allowed: The keyword must not be specified on a and area elements.
Hyperlink: The keyword may be specified on a and area elements; it creates a hyperlink.
External Resource: The keyword may be specified on a and area elements; it creates an external resource link.
Hyperlink Annotation: The keyword may be specified on a and area elements; it annotates other hyperlinks created by the element.

Brief description

A short non-normative description of what the keyword's meaning is.

Specification

A link to a more detailed description of the keyword's semantics and requirements. It could be another page on the Wiki, or a link to an external page.

Synonyms

A list of other keyword values that have exactly the same processing requirements. Authors should not use the values defined to be synonyms, they are only intended to allow user agents to support legacy content. Anyone may remove synonyms that are not used in practice; only names that need to be processed as synonyms for compatibility with legacy content are to be registered in this way.

Status

One of the following:

Proposed: The keyword has not received wide peer review and approval. Someone has proposed it and is, or soon will be, using it.
Ratified: The keyword has received wide peer review and approval. It has a specification that unambiguously defines how to handle pages that use the keyword, including when they use it in incorrect ways.
Discontinued: The keyword has received wide peer review and it has been found wanting. Existing pages are using this keyword, but new pages should avoid it. The "brief description" and "specification" entries will give details of what authors should use instead, if anything.

If a keyword is found to be redundant with existing values, it should be removed and listed as a synonym for the existing value.

If a keyword is registered in the "proposed" state for a period of a month or more without being used or specified, then it may be removed from the registry.

If a keyword is added with the "proposed" status and found to be redundant with existing values, it should be removed and listed as a synonym for the existing value. If a keyword is added with the "proposed" status and found to be harmful, then it should be changed to "discontinued" status.

Anyone can change the status at any time, but should only do so in accordance with the definitions above.

Conformance checkers may use the information given on the microformats wiki existing-rel-values page to establish if a value is allowed or not: values defined in this specification or marked as "proposed" or "ratified" must be accepted when used on the elements for which they apply as described in the "Effect on..." field, whereas values marked as "discontinued" or values not containing a U+003A COLON character but not listed in either this specification or on the aforementioned page must be rejected as invalid. The remaining values must be accepted as valid if they are absolute URLs containing US-ASCII characters only and rejected otherwise. Conformance checkers may cache this information (e.g. for performance reasons or to avoid the use of unreliable network connectivity).

Note: Even URL-valued link types are compared ASCII-case-insensitively. Validators might choose to warn about characters U+0041 (LATIN CAPITAL LETTER A) through U+005A (LATIN CAPITAL LETTER Z) (inclusive) in the pre-case-folded form of link types that contain a colon.

When an author uses a new type not defined by either this specification or the Wiki page, conformance checkers should offer to add the value to the Wiki, with the details described above, with the "proposed" status.

Types defined as extensions in the microformats wiki existing-rel-values page with the status "proposed" or "ratified" may be used with the rel attribute on link, a, and area elements in accordance to the "Effect on..." field. [MFREL]

4.7 Edits

The ins and del elements represent edits to the document.

4.7.1 The `ins` element

Categories:: Flow content.; Phrasing content.; Palpable content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Transparent.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes; cite — Link to the source of the quotation or more information about the edit; datetime — Date and (optionally) time of the change
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses the HTMLModElement interface.

The ins element represents an addition to the document.

The following represents the addition of a single paragraph:

<aside>
 <ins>
  <p> I like fruit. </p>
 </ins>
</aside>

As does the following, because everything in the aside element here counts as phrasing content and therefore there is just one paragraph:

<aside>
 <ins>
  Apples are <em>tasty</em>.
 </ins>
 <ins>
  So are pears.
 </ins>
</aside>

ins elements should not cross implied paragraph boundaries.

The following example represents the addition of two paragraphs, the second of which was inserted in two parts. The first ins element in this example thus crosses a paragraph boundary, which is considered poor form.

<aside>
 <!-- don't do this -->
 <ins datetime="2005-03-16 00:00Z">
  <p> I like fruit. </p>
  Apples are <em>tasty</em>.
 </ins>
 <ins datetime="2007-12-19 00:00Z">
  So are pears.
 </ins>
</aside>

Here is a better way of marking this up. It uses more elements, but none of the elements cross implied paragraph boundaries.

<aside>
 <ins datetime="2005-03-16 00:00Z">
  <p> I like fruit. </p>
 </ins>
 <ins datetime="2005-03-16 00:00Z">
  Apples are <em>tasty</em>.
 </ins>
 <ins datetime="2007-12-19 00:00Z">
  So are pears.
 </ins>
</aside>

4.7.2 The `del` element

Categories:: Flow content.; Phrasing content.
Contexts in which this element can be used:: Where phrasing content is expected.
Content model:: Transparent.
Tag omission in text/html:: Neither tag is omissible.
Content attributes:: Global attributes; cite — Link to the source of the quotation or more information about the edit; datetime — Date and (optionally) time of the change
Allowed ARIA role attribute values:: Any role value.
Allowed ARIA State and Property Attributes:: Global aria-* attributes; Any aria-* attributes applicable to the allowed roles.
DOM interface:: Uses the HTMLModElement interface.

The del element represents a removal from the document.

del elements should not cross implied paragraph boundaries.

The following shows a "to do" list where items that have been done are crossed-off with the date and time of their completion.

<h1>To Do</h1>
<ul>
 <li>Empty the dishwasher</li>
 <li><del datetime="2009-10-11T01:25-07:00">Watch Walter Lewin's lectures</del></li>
 <li><del datetime="2009-10-10T23:38-07:00">Download more tracks</del></li>
 <li>Buy a printer</li>
</ul>

4.7.3 Attributes common to `ins` and `del` elements

The cite attribute may be used to specify the address of a document that explains the change. When that document is long, for instance the minutes of a meeting, authors are encouraged to include a fragment identifier pointing to the specific part of that document that discusses the change.

If the cite attribute is present, it must be a valid URL potentially surrounded by spaces that explains the change. To obtain the corresponding citation link, the value of the attribute must be resolved relative to the element. User agents may allow users to follow such citation links, but they are primarily intended for private use (e.g. by server-side scripts collecting statistics about a site's edits), not for readers.

The datetime attribute may be used to specify the time and date of the change.

If present, the datetime attribute's value must be a valid date string with optional time.

User agents must parse the datetime attribute according to the parse a date or time string algorithm. If that doesn't return a date or a global date and time, then the modification has no associated timestamp (the value is non-conforming; it is not a valid date string with optional time). Otherwise, the modification is marked as having been made at the given date or global date and time. If the given value is a global date and time then user agents should use the associated time-zone offset information to determine which time zone to present the given datetime in.

This value may be shown to the user, but it is primarily intended for private use.

The ins and del elements must implement the HTMLModElement interface:

interface HTMLModElement : HTMLElement {
  attribute DOMString cite;
  attribute DOMString dateTime;
};

The cite IDL attribute must reflect the element's cite content attribute. The dateTime IDL attribute must reflect the element's datetime content attribute.

4.7.4 Edits and paragraphs

This section is non-normative.

Since the ins and del elements do not affect paragraphing, it is possible, in some cases where paragraphs are implied (without explicit p elements), for an ins or del element to span both an entire paragraph or other non-phrasing content elements and part of another paragraph. For example:

<section>
 <ins>
  <p>
   This is a paragraph that was inserted.
  </p>
  This is another paragraph whose first sentence was inserted
  at the same time as the paragraph above.
 </ins>
 This is a second sentence, which was there all along.
</section>

By only wrapping some paragraphs in p elements, one can even get the end of one paragraph, a whole second paragraph, and the start of a third paragraph to be covered by the same ins or del element (though this is very confusing, and not considered good practice):

<section>
 This is the first paragraph. <ins>This sentence was
 inserted.
 <p>This second paragraph was inserted.</p>
 This sentence was inserted too.</ins> This is the
 third paragraph in this example.
 <!-- (don't do this) -->
</section>

However, due to the way implied paragraphs are defined, it is not possible to mark up the end of one paragraph and the start of the very next one using the same ins or del element. You instead have to use one (or two) p element(s) and two ins or del elements, as for example:

<section>
 <p>This is the first paragraph. <del>This sentence was
 deleted.</del></p>
 <p><del>This sentence was deleted too.</del> That
 sentence needed a separate &lt;del&gt; element.</p>
</section>

Partly because of the confusion described above, authors are strongly encouraged to always mark up all paragraphs with the p element, instead of having ins or del elements that cross implied paragraphs boundaries.

4.7.5 Edits and lists

This section is non-normative.

The content models of the ol and ul elements do not allow ins and del elements as children. Lists always represent all their items, including items that would otherwise have been marked as deleted.

To indicate that an item is inserted or deleted, an ins or del element can be wrapped around the contents of the li element. To indicate that an item has been replaced by another, a single li element can have one or more del elements followed by one or more ins elements.

In the following example, a list that started empty had items added and removed from it over time. The bits in the example that have been emphasized show the parts that are the "current" state of the list. The list item numbers don't take into account the edits, though.

<h1>Stop-ship bugs</h1>
<ol>
 <li><ins datetime="2008-02-12T15:20Z">Bug 225:
 Rain detector doesn't work in snow</ins></li>
 <li><del datetime="2008-03-01T20:22Z"><ins datetime="2008-02-14T12:02Z">Bug 228:
 Water buffer overflows in April</ins></del></li>
 <li><ins datetime="2008-02-16T13:50Z">Bug 230:
 Water heater doesn't use renewable fuels</ins></li>
 <li><del datetime="2008-02-20T21:15Z"><ins datetime="2008-02-16T14:25Z">Bug 232:
 Carbon dioxide emissions detected after startup</ins></del></li>
</ol>

In the following example, a list that started with just fruit was replaced by a list with just colours.

<h1>List of <del>fruits</del><ins>colours</ins></h1>
<ul>
 <li><del>Lime</del><ins>Green</ins></li>
 <li><del>Apple</del></li>
 <li>Orange</li>
 <li><del>Pear</del></li>
 <li><ins>Teal</ins></li>
 <li><del>Lemon</del><ins>Yellow</ins></li>
 <li>Olive</li>
 <li><ins>Purple</ins></li>
</ul>

4.7.6 Edits and tables

This section is non-normative.

The elements that form part of the table model have complicated content model requirements that do not allow for the ins and del elements, so indicating edits to a table can be difficult.

To indicate that an entire row or an entire column has been added or removed, the entire contents of each cell in that row or column can be wrapped in ins or del elements (respectively).

Here, a table's row has been added:

<table>
 <thead>
  <tr> <th> Game name           <th> Game publisher   <th> Verdict
 <tbody>
  <tr> <td> Diablo 2            <td> Blizzard         <td> 8/10
  <tr> <td> Portal              <td> Valve            <td> 10/10
  <tr> <td> <ins>Portal 2</ins> <td> <ins>Valve</ins> <td> <ins>10/10</ins>
</table>

Here, a column has been removed (the time at which it was removed is given also, as is a link to the page explaining why):

<table>
 <thead>
  <tr> <th> Game name           <th> Game publisher   <th> <del cite="/edits/r192" datetime="2011-05-02 14:23Z">Verdict</del>
 <tbody>
  <tr> <td> Diablo 2            <td> Blizzard         <td> <del cite="/edits/r192" datetime="2011-05-02 14:23Z">8/10</del>
  <tr> <td> Portal              <td> Valve            <td> <del cite="/edits/r192" datetime="2011-05-02 14:23Z">10/10</del>
  <tr> <td> Portal 2            <td> Valve            <td> <del cite="/edits/r192" datetime="2011-05-02 14:23Z">10/10</del>
</table>

Generally speaking, there is no good way to indicate more complicated edits (e.g. that a cell was removed, moving all subsequent cells up or to the left).

4.8 Embedded content

4.8.1 Introduction

This section is non-normative.

To embed an image in HTML, when there is only a single image resource, use the img element and its src attribute.

<h2>From today's featured article</h2>
<img src="/uploads/100-marie-lloyd.jpg" alt="" width="100" height="150">
<p><b><a href="/wiki/Marie_Lloyd">Marie Lloyd</a></b> (1870–1922)
was an English <a href="/wiki/Music_hall">music hall</a> singer, ...

However, there are a number of situations for which the author might wish to use multiple image resources that the user agent can choose from:

Different users might have different environmental characteristics:
- The users' physical screen size might be different from one another.
  
  A mobile phone's screen might be 4 inches diagonally, while a laptop's screen might be 14 inches diagonally.
  
  This is only relevant when an image's rendered size depends on the viewport size.
- The users' screen pixel density might be different from one another.
  
  A mobile phone's screen might have three times as many physical pixels per inch compared to another mobile phone's screen, regardless of their physical screen size.
- The users' zoom level might be different from one another, or might change for a single user over time.
  
  A user might zoom in to a particular image to be able to get a more detailed look.
  
  The zoom level and the screen pixel density (the previous point) can both affect the number of physical screen pixels per CSS pixel. This ratio is usually referred to as device-pixel-ratio.
- The users' screen orientation might be different from one another, or might change for a single user over time.
  
  A tablet can be held upright or rotated 90 degrees, so that the screen is either "portrait" or "landscape".
- The users' network speed, network latency and bandwidth cost might be different from one another, or might change for a single user over time.
  
  A user might be on a fast, low-latency and constant-cost connection while at work, on a slow, low-latency and constant-cost connection while at home, and on a variable-speed, high-latency and variable-cost connection anywhere else.
Authors might want to show the same image content but with different rendered size depending on, usually, the width of the viewport. This is usually referred to as viewport-based selection.

A Web page might have a banner at the top that always spans the entire viewport width. In this case, the rendered size of the image depends on the physical size of the screen (assuming a maximised browser window).

Another Web page might have images in columns, with a single column for screens with a small physical size, two columns for screens with medium physical size, and three columns for screens with big physical size, with the images varying in rendered size in each case to fill up the viewport. In this case, the rendered size of an image might be bigger in the one-column layout compared to the two-column layout, despite the screen being smaller.
Authors might want to show different image content depending on the rendered size of the image. This is usually referred to as art direction.

When a Web page is viewed on a screen with a large physical size (assuming a maximised browser window), the author might wish to include some less relevant parts surrounding the critical part of the image. When the same Web page is viewed on a screen with a small physical size, the author might wish to show only the critical part of the image.
Authors might want to show the same image content but using different image formats, depending on which image formats the user agent supports. This is usually referred to as image format-based selection.

A Web page might have some images in the JPEG, WebP and JPEG XR image formats, with the latter two having better compression abilities compared to JPEG. Since different user agents can support different image formats, with some formats offering better compression ratios, the author would like to serve the better formats to user agents that support them, while providing JPEG fallback for user agents that don't.

The above situations are not mutually exclusive. For example, it is reasonable to combine different resources for different device-pixel-ratio with different resources for art direction.

While it is possible to solve these problems using scripting, doing so introduces some other problems:

Some user agents aggressively download images specified in the HTML markup, before scripts have had a chance to run, so that Web pages complete loading sooner. If a script changes which image to download, the user agent will potentially start two separate downloads, which can instead cause worse page loading performance.
If the author avoids specifying any image in the HTML markup and instead instantiates a single download from script, that avoids the double download problem above but then no image will be downloaded at all for users with scripting disabled and the aggressive image downloading optimisation will also be disabled.

With this in mind, this specification introduces a number of features to address the above problems in a declarative manner.

Device-pixel-ratio-based selection when the rendered size of the image is fixed

The src and srcset attributes on the img element can be used, using the x descriptor, to provide multiple images that only vary in their size (the smaller image is a scaled-down version of the bigger image).

The x descriptor is not appropriate when the rendered size of the image depends on the viewport width (viewport-based selection), but can be used together with art direction.

<h2>From today's featured article</h2>
<img src="/uploads/100-marie-lloyd.jpg"
     srcset="/uploads/150-marie-lloyd.jpg 1.5x, /uploads/200-marie-lloyd.jpg 2x"
     alt="" width="100" height="150">
<p><b><a href="/wiki/Marie_Lloyd">Marie Lloyd</a></b> (1870–1922)
was an English <a href="/wiki/Music_hall">music hall</a> singer, ...

The user agent can choose any of the given resources depending on the user's screen's pixel density, zoom level, and possibly other factors such as the user's network conditions.

For backwards compatibility with older user agents that don't yet understand the srcset attribute, one of the URLs is specified in the img element's src attribute. This will result in something useful (though perhaps lower-resolution than the user would like) being displayed even in older user agents. For new user agents, the src attribute participates in the resource selection, as if it was specified in srcset with a 1x descriptor.

The image's rendered size is given in the width and height attributes, which allows the user agent to allocate space for the image before it is downloaded.

The srcset and sizes attributes can be used, using the w descriptor, to provide multiple images that only vary in their size (the smaller image is a scaled-down version of the bigger image).

In this example, a banner image takes up the entire viewport width (using appropriate CSS).

<h1><img sizes="100vw" srcset="wolf-400.jpg 400w, wolf-800.jpg 800w, wolf-1600.jpg 1600w"
     src="wolf-400.jpg" alt="The rad wolf"></h1>

The user agent will calculate the effective pixel density of each image from the specified w descriptors and the specified rendered size in the sizes attribute. It can then choose any of the given resources depending on the user's screen's pixel density, zoom level, and possibly other factors such as the user's network conditions.

If the user's screen is 320 CSS pixels wide, this is equivalent to specifying wolf-400.jpg 1.25x, wolf-800.jpg 2.5x, wolf-1600.jpg 5x. On the other hand, if the user's screen is 1200 CSS pixels wide, this is equivalent to specifying wolf-400.jpg 0.33x, wolf-800.jpg 0.67x, wolf-1600.jpg 1.33x. By using the w descriptors and the sizes attribute, the user agent can choose the correct image source to download regardless of how large the user's device is.

For backwards compatibility, one of the URLs is specified in the img element's src attribute. In new user agents, the src attribute is ignored when the srcset attribute uses w descriptors.

In this example, the Web page has three layouts depending on the width of the viewport. The narrow layout has one column of images (the width of each image is about 100%), the middle layout has two columns of images (the width of each image is about 50%), and the widest layout has three columns of images, and some page margin (the width of each image is about 33%). It breaks between these layouts when the viewport is 30em wide and 50em wide, respectively.

<img sizes="(max-width: 30em) 100vw, (max-width: 50em) 50vw, calc(33vw - 100px)"
     srcset="swing-200.jpg 200w, swing-400.jpg 400w, swing-800.jpg 800w, swing-1600.jpg 1600w"
     src="swing-400.jpg" alt="Kettlebell Swing">

The sizes attribute sets up the layout breakpoints at 30em and 50em, and declares the image sizes between these breakpoints to be 100vw, 50vw, or calc(33vw - 100px). These sizes do not necessarily have to match up exactly with the actual image width as specified in the CSS.

The user agent will pick a width from the sizes attribute, using the first item with a <media-condition> (the part in parentheses) that evaluates to true, or using the last item (calc(33vw - 100px)) if they all evaluate to false.

For example, if the viewport width is 29em, then (max-width: 30em) evaluates to true and 100vw is used, so the image size, for the purpose of resource selection, is 29em. If the viewport width is instead 32em, then (max-width: 30em) evaluates to false, but (max-width: 50em) evaluates to true and 50vw is used, so the image size, for the purpose of resource selection, is 16em (half the viewport width). Notice that the slightly wider viewport results in a smaller image because of the different layout.

The user agent can then calculate the effective pixel density and choose an appropriate resource similarly to the previous example.

Art direction-based selection

The picture element and the source element, together with the media attribute, can be used, to provide multiple images that vary the image content (for instance the smaller image might be a cropped version of the bigger image).

<picture>
  <source media="(min-width: 45em)" srcset="large.jpg">
  <source media="(min-width: 32em)" srcset="med.jpg">
  <img src="small.jpg" alt="The president giving an award.">
</picture>

The user agent will choose the first source element for which the media query in the media attribute matches, and then choose an appropriate URL from its srcset attribute.

The rendered size of the image varies depending on which resource is chosen. To specify dimensions that the user agent can use before having downloaded the image, CSS can be used.

img { width: 300px; height: 300px }
@media (min-width: 32em) { img { width: 500px; height:300px } }
@media (min-width: 45em) { img { width: 700px; height:400px } }

This example combines art direction- and device-pixel-ratio-based selection. A banner that takes half the viewport is provided in two versions, one for wide screens and one for narrow screens.

<h1>
 <picture>
  <source media="(max-width: 500px)" srcset="banner-phone.jpeg, banner-phone-HD.jpeg 2x">
  <img src="banner.jpeg" srcset="banner-HD.jpeg 2x" alt="The Breakfast Combo">
 </picture>
</h1>

Image format-based selection

The type attribute on the source element can be used, to provide multiple images in different formats.

<h2>From today's featured article</h2>
<picture>
 <source srcset="/uploads/100-marie-lloyd.webp" type="image/webp">
 <source srcset="/uploads/100-marie-lloyd.jxr" type="image/vnd.ms-photo">
 <img src="/uploads/100-marie-lloyd.jpg" alt="" width="100" height="150">
</picture>
<p><b><a href="/wiki/Marie_Lloyd">Marie Lloyd</a></b> (1870–1922)
was an English <a href="/wiki/Music_hall">music hall</a> singer, ...

In this example, the user agent will choose the first source that has a type attribute with a supported MIME type. If the user agent supports WebP images, the first source element will be chosen. If not, but the user agent does support JPEG XR images, the second source element will be chosen. If neither of those formats are supported, the img element will be chosen.

4.8.1.1 Adaptive images

This section is non-normative.

CSS and media queries can be used to construct graphical page layouts that adapt dynamically to the user's environment, in particular to different viewport dimensions and pixel densities. For content, however, CSS does not help; instead, we have the img element's srcset attribute and the picture element. This section walks through a sample case showing how to use these features.

Consider a situation where on wide screens (wider than 600 CSS pixels) a 300×150 image named a-rectangle.png is to be used, but on smaller screens (600 CSS pixels and less), a smaller 100×100 image called a-square.png is to be used. The markup for this would look like this:

<figure>
 <picture>
  <source srcset="a-square.png" media="(max-width: 600px)">
  <img src="a-rectangle.png" alt="Barney Frank wears a suit and glasses.">
 </picture>
 <figcaption>Barney Frank, 2011</figcaption>
</figure>

For details on what to put in the alt attribute, see the Requirements for providing text to act as an alternative for images section.

The problem with this is that the user agent does not necessarily know what dimensions to use for the image when the image is loading. To avoid the layout having to be reflowed multiple times as the page is loading, CSS and CSS media queries can be used to provide the dimensions:

<figure>
 <style scoped>
  #a { width: 300px; height: 150px; }
  @media (max-width: 600px) { #a { width: 100px; height: 100px; } }
 </style>
 <picture>
  <source srcset="a-square.png" media="(max-width: 600px)">
  <img src="a-rectangle.png" alt="Barney Frank wears a suit and glasses." id="a">
 </picture>
 <figcaption>Barney Frank, 2011</figcaption>
</figure>

Alternatively, the width and height attributes can be used to provide the width for legacy user agents, using CSS just for the user agents that support picture:

<figure>
 <style scoped media="(max-width: 600px)">
  #a { width: 100px; height: 100px; }
 </style>
 <picture>
  <source srcset="a-square.png" media="(max-width: 600px)">
  <img src="a-rectangle.png" width="300" height="150"
  alt="Barney Frank wears a suit and glasses." id="a">
 </picture>
 <figcaption>Barney Frank, 2011</figcaption>
</figure>

The img element is used with the src attribute, which gives the URL of the image to use for legacy user agents that do not support the picture element. This leads to a question of which image to provide in the src attribute.

If the author wants the biggest image in legacy user agents, the markup could be as follows:

<picture>
 <source srcset="pear-mobile.jpeg" media="(max-width: 720px)">
 <source srcset="pear-tablet.jpeg" media="(max-width: 1280px)">
 <img src="pear-desktop.jpeg" alt="The pear is juicy.">
</picture>

However, if legacy mobile user agents are more important, one can list all three images in the source elements, overriding the src attribute entirely.

<picture>
 <source srcset="pear-mobile.jpeg" media="(max-width: 720px)">
 <source srcset="pear-tablet.jpeg" media="(max-width: 1280px)">
 <source srcset="pear-desktop.jpeg">
 <img src="pear-mobile.jpeg" alt="The pear is juicy.">
</picture>

Since at this point the src attribute is actually being ignored entirely by picture-supporting user agents, the src attribute can default to any image, including one that is neither the smallest nor biggest:

<picture>
 <source srcset="pear-mobile.jpeg" media="(max-width: 720px)">
 <source srcset="pear-tablet.jpeg" media="(max-width: 1280px)">
 <source srcset="pear-desktop.jpeg">
 <img src="pear-tablet.jpeg" alt="The pear is juicy.">
</picture>

Above the max-width media feature is used, giving the maximum (viewport) dimensions that an image is intended for. It is also possible to use min-width instead.

<picture>
 <source srcset="pear-desktop.jpeg" media="(min-width: 1281px)">
 <source srcset="pear-tablet.jpeg" media="(min-width: 721px)">
 <img src="pear-mobile.jpeg" alt="The pear is juicy.">
</picture>

4.8.2 The `picture` element

Where embedded content is expected.

Zero or more source elements, followed by one img element, optionally intermixed with script-supporting elements.

Neither tag is omissible.

Allowed ARIA role attribute values:

None

interface HTMLPictureElement : HTMLElement {};

The picture element is a container which provides multiple sources to its contained img element to allow authors to declaratively control or give hints to the user agent about which image resource to use, based on the screen pixel density, viewport size, image format, and other factors. It represents its children.

The picture element is somewhat different from the similar-looking video and audio elements. While all of them contain source elements, the source element's src attribute has no meaning when the element is nested within a picture element, and the resource selection algorithm is different. As well, the picture element itself does not display anything; it merely provides a context for its contained img element that enables it to choose from multiple URLs.

4.8.3 The `source` element when used with the `picture` element

Same as for the source element.

As a child of a picture element, before the img element.

Same as for the source element.

srcset

sizes

media

type

Allowed ARIA role attribute values:

None

partial interface HTMLSourceElement {
           attribute DOMString srcset;
           attribute DOMString sizes;
           attribute DOMString media;
};

The authoring requirements in this section only apply if the source element has a parent that is a picture element.

The source element allows authors to specify multiple alternative source sets for img elements. It does not represent anything on its own.

The srcset attribute must be present, and must consist of one or more image candidate strings, each separated from the next by a U+002C COMMA character (,). If an image candidate string contains no descriptors and no space characters after the URL, the following image candidate string, if there is one, must begin with one or more space characters.

If the srcset attribute has any image candidate strings using a width descriptor, the sizes attribute must also be present, and the value must be a valid source size list.

The media attributes may also be present. If present, the value must contain a valid media query list.

The type attribute may also be present. If present, the value must be a valid MIME type. It gives the type of the images in the source set, to allow the user agent to skip to the next source element if it does not support the given type.

If the type attribute is not specified, the user agent will not select a different source element if it finds that it does not support the image format after fetching it.

When a source element has a following sibling source element or img element with a srcset attribute specified, it must have at least one of the following:

A media attribute specified with a value that, after stripping leading and trailing whitespace, is not the empty string and is not an ASCII case-insensitive match for the string "all".
A type attribute specified.

The src attribute must not be present.

The IDL attributes srcset, sizes and media must reflect the respective content attributes of the same name.

4.8.4 The `img` element

Form-associated element.

If the element has a usemap attribute: Interactive content.

Where embedded content is expected.

Empty.

No end tag.

alt — Replacement text for use when images are not available

src — Address of the resource

srcset — Images to use in different situations (e.g. high-resolution displays, small monitors, etc)

sizes

crossorigin — How the element handles crossorigin requests

usemap — Name of image map to use

ismap — Whether the image is a server-side image map

width — Horizontal dimension

height — Vertical dimension

Allowed ARIA role attribute values:

presentation role only, for an img element whose alt attribute's value is empty (alt=""), otherwise any role value.

Any aria-* attributes applicable to the allowed roles.