From W3C Wiki
The <link> element allows authors to link their document to other resources.
- A link element must have rel attribute.
href= URL potentially surrounded by spaces
Specifies a URL that provides the destination of the link.
rel= set of space-separated tokens
Specifies a list of tokens that specify the relationship between the document containing the link and the destination indicated by the link.Two categories of links can be created using the link element: Links to external resources and hyperlinks:
|alternate||Hyperlink||Gives alternate representations of the current document.|
|archives||Hyperlink||Provides a link to a collection of records, documents, or other materials of historical interest.|
|author||Hyperlink||Gives a link to the current document's author.|
|first||Hyperlink||Indicates that the current document is a part of a series, and that the first document in the series is the referenced document.|
|help||Hyperlink||Provides a link to context-sensitive help.|
|icon||External Resource||Imports an icon to represent the current document.|
|index||Hyperlink||Gives a link to the document that provides a table of contents or index listing the current document.|
|last||Hyperlink||Indicates that the current document is a part of a series, and that the last document in the series is the referenced document.|
|license||Hyperlink||Indicates that the main content of the current document is covered by the copyright license described by the referenced document.|
|next||Hyperlink||Indicates that the current document is a part of a series, and that the next document in the series is the referenced document.|
|pingback||External Resource||Gives the address of the pingback server that handles pingbacks to the current document.|
|prefetch||External Resource||Specifies that the target resource should be preemptively cached.|
|prev||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||Gives a link to a resource that can be used to search through the current document and its related pages.|
|stylesheet||External Resource||Imports a stylesheet.|
|sidebar||Hyperlink||Specifies that the referenced document, if retrieved, is intended to be shown in the browser's sidebar (if it has one).|
|tag||Hyperlink||Gives a tag (identified by the given address) that applies to the current document.|
|up||Hyperlink||Provides a link to a document giving the context for the current document.|
media= media-query list
The media for which the destination of the hyperlink was designed.
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 default, if the media attribute is omitted, is "all", meaning that by default links apply to all media.
hreflang= language tag
The language of the destination of the hyperlink.
A valid language tag, as defined in [BCP47].
type= A valid MIME type that destination of the hyperlink.
gives the MIME type of the linked resource.
The default value for the type attribute, which is used if the attribute is absent, is "text/css".
sizes= icon sizes
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.
- Also, the title attribute has special semantics on this element. The exception is for style sheet links, where the title attribute defines alternative style sheet sets.
See also global attributes.
Here, a set of link elements provide some style sheets:
<head> <!-- 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"> </head>
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:
<head> <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"> </head>
The HTML5 specification defines the <link> element in 4.2.5 The link element.