Web Content Accessibility Guidelines 2.0 -- Review Version

Introduction

This section is informative.

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Web Content Accessibility Guidelines (WCAG) 2.0 defines how to make Web content more accessible to people with disabilities[begin delete], and older people with changing abilities due to aging[end delete]. Accessibility involves a wide range of disabilities, including visual, auditory, physical, speech, cognitive, language, learning, and neurological disabilities. [begin add]These guidelines also often make content more usable in general. [2011] [end add] Although these guidelines cover a wide range of issues, they are not able to address the needs of people with all types, degrees and combinations of disabilities.[begin add] This document also makes Web content more usable by older individuals with changing abilities due to aging. [end add]

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WCAG 2.0 is developed through the W3C process in cooperation with individuals and organizations around the world, with a goal of providing a shared standard for Web content accessibility that meets the needs of individuals, organizations, and governments internationally. WCAG 2.0 builds on WCAG 1.0 [WCAG10] and is designed to apply broadly to different Web technologies now and in the future, and to be testable with a combination of automated testing and human evaluation. For an introduction to WCAG, see the Web Content Accessibility Guidelines (WCAG) Overview.

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Web accessibility depends not only on accessible content, but also on accessible Web browsers and other user agents. Authoring tools also have an important role in Web accessibility. For an overview of how these components of Web development and interaction work together, see:

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This is a Working Draft of the Web Content Accessibility Guidelines (WCAG) version 2.0. WCAG is developed through the W3C process in cooperation with individuals and organizations around the world, with a goal of providing a single shared standard for Web accessibility that meets the needs of individuals, organizations, and governments internationally.

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WCAG 2.0 builds upon the work of WCAG 1.0 [WCAG10] with provisions that are more testable and that extend to a broader range of technologies including many that are new and evolving. WCAG 2.0 has been created to be technology independent. That is, the guidelines and Success Criteria in WCAG 2.0 can be applied across a wide range of existing and emerging Web technologies. Rather than specifying what technologies to use, WCAG 2.0 lays out general guidelines for using technologies along with specific testable Success Criteria for guiding and evaluating the use of the technologies.

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WCAG 2.0 provides requirements for making content (Web content) more accessible to a wide range of people with disabilities, including blindness and low vision, deafness and hearing loss, learning disabilities, cognitive limitations, limited movement, speech disabilities, and others. Because many people develop vision, hearing, cognitive or motion impairments as they age, following these guidelines will make your Web content more usable by many older users. These guidelines also often make Web content more accessible to the general public as well. However, even content that completely conforms to WCAG may not be fully accessible to every person with a disability.

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WCAG 2.0 covers a wide range of recommendations for making Web content more accessible. The guidelines do not include standard usability recommendations except where they have a significantly greater impact on people with disabilities than on other people.

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Although some of the accessibility issues of people with cognitive, language, and learning disabilities are addressed by WCAG 2.0, either directly or through assistive technologies, the WCAG 2.0 guidelines do not address many areas of need for people with these disabilities. There is a need for more research and development in this important area.

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Components of Web Accessibility

It is important to note that Web content is just one aspect of accessibility. Just as important as accessible Web content is the availability of accessible browsers (and other user agents) that can adapt and present the content in the best form for the user. Accessible Web technologies and accessible tools for creating Web content are also important. For an overview of the different components of accessibility and how they work together see:

Essential Components of Web Accessibility - Explains how the Web Content Accessibility Guidelines work with the other WAI guidelines and with assistive technologies to provide access to the Web by people with disabilities.
User Agent Accessibility Guidelines (UAAG) Overview - Introduces guidelines on the design of accessible Browsers and other user agents.
Authoring Tool Accessibility Guidelines (ATAG) Overview - Introduces guidelines on the design of authoring and evaluation tools.

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WCAG 2.0 Layers of Guidance

The individuals and organizations that use WCAG vary widely and include Webmasters, policy makers, purchasing agents, teachers, and students. In order to meet the varying needs several layers of guidance are provided including overall principles, general guidelines, testable Success Criteria and a rich collection of sufficient techniques, advisory techniques and documented failures with examples, resource links and code.

Principles - At the top are four principles that provide the foundation for Web accessibility: perceivable, operable, understandable, and robust. See also Understanding the Four Principles of Accessibility.
Guidelines - Under the principles are guidelines. The 12 guidelines provide the basic goals that authors should work toward in order to make content more accessible to users with different disabilities. These guidelines are not testable but provide the framework and overall objectives to help authors understand the Success Criteria and better implement the techniques.
Success Criteria - For each guideline, testable Success Criteria are provided to allow WCAG 2.0 to be used [begin delete]in design specification, purchasing, regulation, contractual agreements, etc. [end delete]where requirements and [begin change]conformance testing[end change] are necessary[begin add] such as in design specification, purchasing, regulation, and contractual agreements[end add]. In order to meet the needs of different groups and different situations, three levels of conformance are defined: A (lowest), AA, AAA (highest). (Additional information on WCAG levels can be found in Understanding Levels of Conformance.)
Sufficient and Advisory Techniques - For each of the guidelines and Success Criteria in the WCAG 2.0 document itself, the working group has also documented a wide variety of techniques. The techniques [begin add]are informative and [end add]fall into two categories: those that are sufficient for meeting the Success Criteria and those that are “advisory" and go beyond what is required by the individual Success Criteria and allow authors to better address the guidelines. See also Sufficient and Advisory Techniques in Understanding WCAG 2.0.

All of these layers of guidance (guidelines, Success Criteria, and sufficient and advisory techniques) work together to provide guidance on how to make content more accessible. Authors are encouraged to view and apply all layers that they are able to, including the advisory techniques, in order to best address the needs of the widest possible range of users.

Note that even content that conforms at the highest level (AAA) will not be accessible to individuals with all types, degrees, or combinations of disability particularly in the cognitive language and learning areas. Authors are encouraged to consider the full range of techniques, including the advisory techniques, as well as to seek relevant advice about current best practice to ensure that Web content is accessible, as far as possible, to this community. [2004] Metadata may assist users in finding content most suitable for their needs. [1957]

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WCAG 2.0 Supporting Documents

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The WCAG 2.0 document [begin delete]itself[end delete] is designed to meet the needs of those who need a stable, referenceable technical standard. [begin delete]For different needs and different types of users, W3C WAI provides additional material. These include:[end delete] [begin add]Other documents, called supporting documents, are based on the WCAG 2.0 document and address other important purposes. Supporting document include:[end add]

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WCAG 2.0 itself is a technical standard designed primarily for Web developers and designers, authoring tool developers, evaluation tool developers, and others who need a technical standard for Web accessibility. Due to the technical and technology-independent nature of the guidelines and Success Criteria, and because they say what needs to be done rather than how to do it, it may sometimes be difficult to use the guidelines or Success Criteria for specific advice for a particular technology (e.g. HTML, XHTML, JavaScript etc).

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In order to provide more concrete examples as well as specific techniques for meeting each of the Success Criteria, three support documents or collections have been developed by the working group to accompany the guidelines. These documents provide very specific guidance that can be used directly to meet the WCAG 2.0 guidelines.

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The overall set of documents from the working group consists of:

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The WCAG 2.0 Guidelines - (this document) - This document provides the guidelines, Success Criteria, conformance specifications as well as the definitions of terms used in the guidelines. The actual guidelines (including Success Criteria) are only 9 pages long.
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WCAG 2.0 Quick Reference - A concise list that includes all of the guidelines, Success Criteria, and techniques for authors to use as they are developing and evaluating Web content.
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Understanding WCAG 2.0 - A guide to understanding and implementing WCAG 2.0. There is a short "Understanding" document for each guideline and Success Criterion in WCAG 2.0 as well as key topics.
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Techniques for WCAG 2.0 - A collection of techniques and known failures, each in a separate document, that includes a description, examples, code and tests.
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See Overview of WCAG 2.0 Documents for a description of the WCAG 2.0 supporting material, including education resources related to WCAG 2.0.

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Additional Resource Documents on WCAG 2.0 and Web Accessibility

In addition to WCAG and its primary reference documents prepared by the WCAG Working group, there are a number of additional resource documents available on WCAG 2.0 and its relationship to Web accessibility. This set of documents will continue to grow even after the WCAG 2.0 is released. Documents available at the time of this document's release include:

Overview of Web Content Accessibility Guidelines (WCAG) 2.0 Documents - Provides an overview of WCAG 2.0 and its various informative support documents
WCAG 2 FAQ - Provides key information on the most commonly asked questions around WCAG 2.0.
WAI Resources on Introducing Web Accessibility - Provides basic information for people who are new to Web accessibility.

Other documents under development include:

Transitioning from WCAG 1.0 to 2.0 - Information to facilitate transitioning from use of WCAG 1.0 to WCAG 2.0.
Application Notes - Provides detailed application information in different areas such as "Designing Accessible Web Forms," or "Creating Basic HTML Web Pages that are Accessible."

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Organization of the WCAG 2.0 Document

The Four Principles

The guidelines and Success Criteria are organized around the following four principles. These four principles lay the foundation necessary for anyone to access and use Web content. Anyone who wants to use the Web must have content that is:

Perceivable - Information and user interface components must be perceivable by users;
Operable - User interface components must be operable by users;
Understandable - Information and operation of user interface must be understandable by users;
Robust - Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies.

The Guidelines

Under each principle there is a list of guidelines that address the principle. There are a total of 12 guidelines. A convenient list of just the guidelines can be found in the table of contents.

Success Criteria

Under each guideline there are Success Criteria that describe specifically what must be achieved in order to conformance [begin delete] to this standard [2184] [end delete]. They are similar to the "checkpoints" in WCAG 1.0. Each Success Criterion is written as a statement that will be either true or false when specific Web content is tested against it.

All WCAG 2.0 Success Criteria are written to be testable. While some can be tested by computer programs, others require human testers for part or all of the test. The same results should be obtained with a high level of confidence when [begin change]the content is tested by those who understand how people with different types of disabilities use the Web [2321] [end change].

Each Success Criterion for a guideline has a link to the section of the Quick Reference document that provides:

sufficient techniques for meeting the Success Criterion,
optional advisory techniques, and
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links to descriptions of the intent of the Success Criteria (including benefits) and examples. [2186]
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Three levels of conformance

WCAG 2.0 Success Criteria are organized into three levels of conformance.

"Level A" conformance: all Level A Success Criteria must be satisfied in order to achieve Level A conformance.
"Level AA" conformance: all Level A and Level AA Success Criteria must be satisfied in order to achieve Level AA conformance.
"Level AAA" conformance: all Level A, AA, and AAA must be satisfied in order to achieve Level AAA conformance.

The word "levels" does not mean that some Success Criteria are more important than others. Each Success Criterion in WCAG 2.0 is essential to some users, and the levels build upon each other. However, even content that conforms at Level AAA may not be fully accessible to every person with a disability or combination of disabilities, especially certain types of severe disabilities.

In general, Level A Success Criteria achieve accessibility by supporting assistive technology while putting the fewest possible limits on presentation. Thus people with a wide range of disabilities using a wide range of assistive technologies, from voice input and eye-tracking devices to screen readers and screen magnifiers, are able to access content in different ways. In other words, Level A Success Criteria support the ability of both mainstream and specialized user agents to adapt content to formats that meet their users' needs.
The Success Criteria in Level AA provide additional support for assistive technology. At the same time, they also support direct access to content by the many people who use conventional user agents without assistive technology. In general, Level AA Success Criteria place more limits on visual presentation and other aspects of content than the Success Criteria in Level A.
Level AAA Success Criteria increase both direct access and access through assistive technology. They place tighter limits on both presentation and content, which means that some types of content may not be able to satisfy this level of conformance.

It is recommended that even if content does not conform at a specific level, that it conform to the extent possible.

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Important Terms in WCAG 2.0

[begin change]WCAG 2.0 includes three important terms that are different from WCAG 1.0.[end change] [begin delete] In some cases, these terms are just clarifications of concepts that have been in use but have not been clearly defined in the past. In other cases, they are terms that match new concepts that have been [begin add]developed to allow for new technologies, potential accessibility issues that result from their use, and strategies that emerge to address these issues[end add] developed to cope with the new technologies that are continually emerging and with the accessibility issues and strategies that are emerging to address them. [2189] [end delete] [begin add]Each of these is introduced briefly below and defined more fully in the glossary.[end add]

Sufficient Techniques: [begin delete]
For each Success Criterion, there is a list of techniques deemed by the Working Group to be sufficient to meet the requirement. For each sufficient technique, there is a test to determine whether the technique has been successfully implemented. If the test(s) for a "sufficient" technique (or combination of techniques) are passed, then that Success Criterion has been satisfied.
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Passing all tests for all sufficient techniques is not necessary. Most Success Criteria have multiple "sufficient techniques" listed. Any of the listed "sufficient techniques" can be used to meet the Success Criterion.
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Note that it is not necessary to meet a Success Criterion using one of the sufficient techniques that have been documented by the WCAG working group. There may be other techniques which are not documented by the working group that would also meet the Success Criterion. The working group went through the effort to document these "sufficient techniques" in order to make it easy for authors to identify techniques that meet each Success Criterion and to have confidence (and evidence) that the techniques meet the Success Criterion. When using other externally-provided techniques to meet WCAG 2.0 requirements, it is important that they be created by individuals or organizations who are knowledgeable about the requirements of WCAG 2.0 and the needs of people with disabilities. The working group will continue to add new "sufficient techniques" as they are identified, developed, or made effective by advances in user agents including assistive technologies.
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Advisory Techniques: [begin delete]
In addition to the sufficient techniques, there are a number of techniques that may enhance accessibility, but did not qualify as sufficient techniques because they are not testable, are not sufficient to meet the full requirements of the Success Criteria, and/or are good and effective techniques in some circumstances but not effective (and therefore sufficient) in others. These are listed as "Advisory Techniques." Authors are encouraged to use these techniques where appropriate. Although using them does not affect conformance, it can enhance accessibility for some users. Many of the advisory techniques are particularly helpful for people with cognitive, language, and learning disabilities, and use of these techniques will improve the accessibility of the content to people with these disabilities.
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Web Page: [begin add]
It is important to note that, in this standard, the term "Web page" includes much more than static HTML pages. It also includes the increasingly dynamic Web pages that are emerging on the Web, including "pages" that can present entire virtual interactive communities. For example, the term "Web page" includes an immersive interactive movie-like experience that you find at a single URL. For more information, see Understanding "Web Page".
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While not an entirely new term, it is important to note that, in this standard, the term "Web page" includes much more than static HTML pages. It also includes the increasingly dynamic Web pages that are emerging on the Web, including "pages" that can present entire virtual interactive communities. Technically a Web page, as defined in the glossary, is "a resource that is referenced by a URI and is not embedded in another resource, plus any other resources that are used in the rendering or intended to be rendered together with it." What this means is that a Web page is whatever you find at the end of a Web address that you visit. It includes Web applications, Webcasts, synchronized media objects and other types of interactive content to which the word "page" may not typically apply. It is in this evolved sense of the concept that the term is used in WCAG 2.0.
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For example, the term "Web page" would include a movie-like interactive shopping environment where the user visually moves about a store dragging products off of the shelves around them and into a visual shopping cart in front of them where clicking on a product causes it to be demonstrated with a specification sheet alongside.
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Programmatically Determined: Several Success Criteria require that content (or certain aspects of content) can be "programmatically determined." This means that the content is delivered in such a way that user agents, including assistive technologies, can [begin add]extract and present this information to users in different modalities. For more information, see Understanding Programmatically Determined.[end add] [begin delete] access the information. A critical element in having anything be "programmatically determined" is that assistive technologies are able to retrieve and use the information. This lets user agents, including assistive technologies, transform the content and present it to the user in different sensory modalities (e.g. vision, hearing) or styles of presentation. If assistive technologies cannot do this, then the information cannot be said to be programmatically determined. [end delete]
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The term was created in order to allow the working group to clearly identify those places where information had to be accessible to assistive technologies (and other user agents acting as accessibility aids) without specifying exactly how this needed to be done. This is important because of the continually changing nature of the technologies. It is important neither to declare things as accessible because they might be in the future (when they aren't now) nor to declare things as inaccessible in a permanent way when they may very well become accessible in the future.
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The use of the term allows the guidelines to identify what needs to be "programmatically determined" in order to meet the guidelines, and then have separate [begin add]documents (the Quick Reference, Understanding, and Technique documents) to list techniques and technologies that meet the requirements, which can be updated over time based on user agent and assistive technology support.[end add] [begin delete], updateable documents (the Quick Reference, Understanding, and Technique documents) list those techniques and technologies that meet the requirements over time. [end delete] [2196]
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Accessibility Supported: [begin add]
An accessibility supported technology is a [begin delete]Web[end delete] technology (HTML, CSS, etc.) that will work with assistive technologies (AT) and the accessibility features of browsers and other user agents. Only [begin delete]Web[end delete] technologies ([begin change]including[end change] features of the technologies), that are "accessibility supported" can be used to conform to WCAG 2.0 Success Criteria. [begin add]Only "accessibility supported" technologies can be used to conform to WCAG 2.0 Success Criteria[end add] Technologies that are not accessibility supported (do not work with AT etc.) can be used, but cannot be used to conform to any Success Criterion.
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[begin add]The [begin change]definition of[end change] "accessibility support" is provided in the Appendix A: Glossary section of these guidelines.[end add] For more information, see Understanding accessibility support in Understanding WCAG 2.0.
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In order for content created with technology (Web content) (such as HTML, CSS, PDF, GIF, MPEG, Flash etc.) to be accessible to people with different types of disabilities, it is essential that the technologies [begin change]used work with the accessibility features of browsers and other user agents, including assistive technologies. In order for something to meet a Success Criterion that requires it to be "programmatically determined," it would need to be implemented using a technology that has assistive technology support.[end change] [2197]
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"Accessibility supported" means supported by users' assistive technologies as well as the accessibility features in browsers and other user agents.
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Authors who don't know which technologies or which aspects and features of a technology have support from assistive technologies should consult documented lists of technologies that are known to have accessibility support. Such lists can make it easier than it is today for an author to identify technologies or features of different technologies that are supported by assistive technologies and can be used to meet the Success Criteria that require assistive technology support (i.e. require that content can be programmatically determined.)
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Note: The requirements for "accessibility support" of Web technologies are provided in the conformance section of these guidelines (See also .)
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WCAG 2.0 Guidelines

This section is normative.

Principle 1: Perceivable - Information and user interface components must be presentable to users in ways they can perceive

Guideline 1.1 Text Alternatives: Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language Understanding Guideline 1.1

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1.1.1 Non-text Content: All non-text content has a text alternative that presents equivalent information, except for the situations listed below. [1992] (Level A) How to Meet 1.1.1 Understanding 1.1.1

Controls, Input: If [begin add]it[end add] [begin delete]non-text content[end delete] is a control or accepts user input, then it has a name that describes its purpose. (See also Guideline 4.1.)
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Media, Test, Sensory: If [begin add]it[end add] [begin delete]non-text content[end delete] is [begin delete]any of the following[end delete] [begin add](1) [end add] synchronized media, [begin add](2) [end add] live audio-only or live video-only content, [begin add](3) [end add]a test or exercise that must be presented in non-text format, [begin add](4) [end add] [begin delete]content [end delete]primarily intended to create a specific sensory experience, then text alternatives at least [begin change]provide descriptive identification of the non-text content[end change] [begin add], or (5) a media alternative to text that is clearly labeled as such [2290] [end add]. (For synchronized media, see also Guideline 1.2.)
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Note: Prerecorded audio-only and video-only files would be covered under Success Criterion 1.1.1, which requires text alternatives that present equivalent information.
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CAPTCHA: If [begin add]it[end add] [begin delete]the purpose of non-text content[end delete] is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided[begin add], and alternative forms of CAPTCHA using output modes for different types of sensory perception[end add] [begin delete]and alternative forms in different modalities[end delete] are provided to accommodate different disabilities.
Decoration, Formatting, Invisible: If [begin add]it[end add] [begin delete]non-text content[end delete] is pure decoration, or used only for visual formatting, or if it is not presented to users, then it is implemented [begin change]in a way[end change] [begin delete]such[end delete] that it can be ignored by assistive technology.

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1.1.2 Live Audio-only: All live audio-only content has a text alternative [1944] (Level AAA) How to Meet 1.1.2 Understanding 1.1.2

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Guideline 1.2 Synchronized Media: Provide synchronized alternatives for synchronized media Understanding Guideline 1.2

1.2.1 Captions (Prerecorded): Captions are provided for prerecorded synchronized media, [begin change]except if the synchronized media is an alternative to text and is clearly labeled as such [2290] [end change]. (Level A) How to Meet 1.2.1 Understanding 1.2.1

1.2.2 Audio Description or Full Text Alternative: Audio description of video, or a full text alternative for synchronized media including any interaction , is provided for prerecorded synchronized media. (Level A) How to Meet 1.2.2 Understanding 1.2.2

Note: For 1.2.2, 1.2.4, and 1.2.7, if all of the information in the video track is already provided in the audio track, no audio description is necessary.

1.2.3 Captions (Live): Captions are provided for live synchronized media. (Level AA) How to Meet 1.2.3 Understanding 1.2.3

Note: If synchronized media is completely computer generated, it is not live and is subject to the requirements for prerecorded synchronized media in WCAG 2.0.

1.2.4 Audio Description: Audio description of video is provided for prerecorded synchronized media. (Level AA) How to Meet 1.2.4 Understanding 1.2.4

1.2.5 Sign Language: Sign language interpretation is provided for [begin add]prerecorded [end add] synchronized media. (Level AAA) How to Meet 1.2.5 Understanding 1.2.5

1.2.6 Audio Description (Extended): Extended audio description of video is provided for prerecorded synchronized media. (Level AAA) How to Meet 1.2.6 Understanding 1.2.6

1.2.7 Full Text Alternative: A full text alternative for synchronized media including any interaction is provided for all prerecorded synchronized media, [begin change]except if the synchronized media is an alternative to text and is clearly labeled as such [2290] [end change]. (Level AAA) How to Meet 1.2.7 Understanding 1.2.7

Guideline 1.3 Adaptable: Create content that can be presented in different ways (for example [begin change]simpler layout [2094] [end change]) without losing information or structure Understanding Guideline 1.3

1.3.1 Info and Relationships: Information[begin add], structure, [2291] [end add] and relationships conveyed through presentation can be programmatically determined or are available in text[begin delete], and notification of changes to these is available to user agent, including assistive technology (as used in this document) [2305] [end delete]. (Level A) How to Meet 1.3.1 Understanding 1.3.1

1.3.2 Meaningful Sequence: When the sequence in which content is presented affects its meaning, a correct reading sequence can be programmatically determined [begin delete] and sequential navigation of interactive components is consistent with that sequence[end delete]. (Level A) How to Meet 1.3.2 Understanding 1.3.2

1.3.3 Sensory Characteristics: [begin add]Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, size, visual location, orientation or sound.[end add] [begin delete]Instructions provided for understanding and operating content do not rely on shape, size, visual location, or orientation of components.[end delete] [2015] (Level A) How to Meet 1.3.3 Understanding 1.3.3

Guideline 1.4 Distinguishable: Make it easier for [begin change]users [2204] [end change] to see and hear content including separating foreground from background Understanding Guideline 1.4

1.4.1 Use of Color: [begin add]Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.[end add] [begin delete]Any information that is conveyed by color differences is also simultaneously visually evident without the color differences.[end delete] (Level A) How to Meet 1.4.1 Understanding 1.4.1

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Note 1: This Success Criterion addresses color perception specifically. Other forms of perception are covered in Guideline 1.3. [2255]

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Note 2: Programmatic access to color and other visual presentation coding is covered in Guideline 1.3.

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1.4.2 Audio Control: If any audio [begin add]on a Web page[end add] plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume which can be set [begin add]to be a different level from the system volume level[end add] [begin delete]independently of the system volume[end delete]. [2131] [2185] (Level A) How to Meet 1.4.2 Understanding 1.4.2

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Note: Since any content that does not meet this Success Criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other Success Criteria or not) must meet this Success Criterion. See Conformance Requirement 5: Non-Interference.

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1.4.3 Contrast (Minimum): Text and images of text have a contrast ratio of at least 5:1, except for the following: [2000] (Level AA) How to Meet 1.4.3 Understanding 1.4.3

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Large Print: Large-scale text and large-scale images of text have a contrast ratio of at least 3:1;
Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are incidental text in an image, or that are not visible to anyone, have no minimum contrast requirement.

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Note: Success Criteria 1.4.3 and 1.4.6 can be met via a contrast control available on or from the page.

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1.4.4 Resize text: [begin add] Text (but not images of text)[end add] [begin delete]Visually rendered text[end delete] can be resized without assistive technology up to 200 percent [begin delete]and down to 50 percent [2112] [end delete]without loss of content or functionality. [2164] (Level AA) How to Meet 1.4.4 Understanding 1.4.4

1.4.5 Images of Text (Limited): When [begin change]the accessibility supported technologies being used can[end change] achieve the visual presentation, text is used to convey information rather than images of text [begin change]except for the following:[end change] [begin delete]the image of the text can be visually customized to the user's requirements.[end delete] (Level AA) How to Meet 1.4.5 Understanding 1.4.5

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Customizable: The image of text can be visuallycustomized to the user's requirements;
Essential: A particular presentation of text is essential to the information being conveyed.

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Note: Logotypes (text that is part of a logo or brand name) are considered essential.

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1.4.6 Contrast (Enhanced): Text and images of text have a contrast ratio of at least 7:1, except for the following: [2000] (Level AAA) How to Meet 1.4.6 Understanding 1.4.6

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Large Print: Large-scale text and large-scale images of text have a contrast ratio of at least 5:1;
Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are incidental text in an image, or that are not visible to anyone, have no minimum contrast requirement.

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Note: Success Criteria 1.4.3 and 1.4.6 can be met via a contrast control available on or from the page.

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1.4.7 Low or No Background Audio: Audio content that is not an audio CAPTCHA and [2355] that contains speech in the foreground does not contain background sounds, background sounds can be turned off, or background sounds are at least 20 decibels lower than the foreground speech content, with the exception of occasional sound effects. (Level AAA) How to Meet 1.4.7 Understanding 1.4.7

Note: Background sound that meets this requirement will be approximately one quarter as loud as the foreground speech content.

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1.4.8 Visual Presentation: For the visual presentation of blocks of text, a mechanism is available to achieve the following: (Level AAA) How to Meet 1.4.8 Understanding 1.4.8

foreground and background colors can be selected by the user
width is no more than 80 characters
text is not aligned on both the left and the right [1253] [569]
line spacing is at least space-and-a-half within paragraphs, and paragraph spacing is larger than line spacing [569]
text is resized without assistive technology up to 200 percent in a way that does not require the user to scroll horizontally to read a line of text

[end add]

[begin add]

1.4.9 Images of Text (Essential): Images of text are only used for pure decoration or where a particular presentation of text is essential to the information being conveyed. (Level AAA) How to Meet 1.4.9 Understanding 1.4.9

Note: Logotypes (text that is part of a logo or brand name) are considered essential.

[2128]

[end add]

Principle 2: Operable - User interface components and navigation must be operable

Guideline 2.1 Keyboard Accessible: Make all functionality available from a keyboard Understanding Guideline 2.1

2.1.1 Keyboard: All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints. (Level A) How to Meet 2.1.1 Understanding 2.1.1

Note 1: This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path dependent input but the underlying function (text input) does not.

Note 2: This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation.

[begin add]

2.1.2 No Keyboard Trap: If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface, and, if it requires more than unmodified arrow or tab keys, the user is advised of the method for moving focus away. (Level A) How to Meet 2.1.2 Understanding 2.1.2

[2222]

[end add]

2.1.3 Keyboard (No Exception): All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes. (Level AAA) How to Meet 2.1.3 Understanding 2.1.3

Guideline 2.2 Enough Time: Provide users with disabilities enough time to read and use content Understanding Guideline 2.2

2.2.1 Timing Adjustable: For each time limit that is set by the content, at least one of the following is true: (Level A) How to Meet 2.2.1 Understanding 2.2.1

Turn off: the user is allowed to turn off the time limit before encountering it; or
Adjust: the user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or
Extend: the user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar [2226] "), and the user is allowed to extend the time limit at least ten times; or
Real-time Exception: the time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or
Essential Exception: the time limit [begin delete]is part of an activity where moving, blinking, scrolling, or auto-updating timing is essential [begin delete](for example, time-based testing) [end delete]and time limits [2227] [end delete] cannot be extended [begin delete]further[end delete] without invalidating the activity; or [1949]
[begin add]
20 Hour Exception: the time limit is longer than 20 hours. [2114]
[end add]

[begin add]

Note: This Success Criterion acts to ensure that changes in content or context as a result of a time limit will not occur unexpectedly, preventing users from completing tasks. While exceptions to Success Criterion 2.2.1 where timing is essential exist, guideline 2.2 in general limits changes in content for no reason. This Success Criterion should be considered in conjunction with Success Criterion 3.2.1 which puts limits on changes of content or context as a result of user action. [2340]

[end add]

2.2.2 Pausing: Moving, blinking, scrolling, or auto-updating information [begin add]on a Web page that lasts for more than [begin change]three[end change] seconds[end add] can be paused by the user unless [begin change]the movement, blinking, scrolling, or auto-updating[end change] is part of an activity where [begin add]the changes are[end add] [begin delete]timing or movement are[end delete] essential. Moving [begin add]or blinking[end add] content that is pure decoration can be stopped or hidden by the user. (Level AA) How to Meet 2.2.2 Understanding 2.2.2

Note 1: For requirements related to flickering or flashing content, refer to Guideline 2.3.

[begin add]

Note 2: Since any content that does not meet this Success Criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other Success Criteria or not) must meet this Success Criterion. See Conformance Requirement 5: Non-Interference.

[end add]

[begin add]

Note 3: Content that is updated from a process, real-time or remote stream is not required to preserve or present information that is generated or received between the initiation of the pause and resuming presentation, as this may not be technically possible, and in many situations could be misleading to do so. [2132]

[end add]

2.2.3 No Timing: Timing is not an essential part of the event or activity presented by the content, except for non-interactive synchronized media and real-time events. (Level AAA) How to Meet 2.2.3 Understanding 2.2.3

2.2.4 Interruptions: Interruptions[begin delete], such as updated content,[end delete] can be postponed or suppressed by the user, except interruptions involving an emergency. (Level AAA) How to Meet 2.2.4 Understanding 2.2.4

2.2.5 Re-authenticating: When an authenticated session expires, the user can continue the activity without loss of data after re-authenticating. (Level AAA) How to Meet 2.2.5 Understanding 2.2.5

[begin change]

Guideline 2.3 Seizures: Do not design content in a way that is known to cause seizures Understanding Guideline 2.3

[end change]

2.3.1 Three Flashes or Below Threshold: [begin add] Web pages do [end add] [begin delete]Content does[end delete] not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds. (Level A) How to Meet 2.3.1 Understanding 2.3.1

[begin add]

[end add]

2.3.2 Three Flashes: [begin add] Web pages do [end add] [begin delete]Content does[end delete] not contain anything that flashes more than three times in any one second period. (Level AAA) How to Meet 2.3.2 Understanding 2.3.2

Guideline 2.4 Navigable: Provide ways to help users with disabilities navigate, find content and determine where they are Understanding Guideline 2.4

2.4.4 Link Purpose (In Context): [begin change]The purpose of each link can be determined from the link text alone, or from the link text together with its programmatically determined link context, except where the purpose of the link would be ambiguous to users in general.[end change] [2020] [2152] [2050] [2249] [1951] (Level A) How to Meet 2.4.4 Understanding 2.4.4

[begin add] [end add]

Principle 3: Understandable - Information and the operation of user interface must be understandable

Guideline 3.1 Readable: Make text content readable and understandable Understanding Guideline 3.1

3.1.1 Language of Page: The default human language of each Web page [begin delete]within the content [end delete]can be programmatically determined. (Level A) How to Meet 3.1.1 Understanding 3.1.1

3.1.2 Language of Parts: The human language of each [begin change]passage[end change] or phrase in the content can be programmatically determined [begin add] except for proper names, technical terms, words of indeterminate language, and words or phrases that have become part of the vernacular of the immediately surrounding text[end add]. [2069] (Level AA) How to Meet 3.1.2 Understanding 3.1.2

[begin delete]

Note: This requirement does not apply to individual words. It also does not apply to proper names, to technical terms or to phrases that have become part of the language of the context in which they are used.

Web Content Accessibility Guidelines 2.0

W3C Working Draft 11 December 2007 -- Review Version

Abstract

Status of this Document

Table of Contents

Appendices

Introduction

Components of Web Accessibility

WCAG 2.0 Layers of Guidance

WCAG 2.0 Supporting Documents

Additional Resource Documents on WCAG 2.0 and Web Accessibility

Organization of the WCAG 2.0 Document

The Four Principles

The Guidelines

Success Criteria

Three levels of conformance

Important Terms in WCAG 2.0

WCAG 2.0 Guidelines

Principle 1: Perceivable - Information and user interface components must be presentable to users in ways they can perceive

Guideline 1.1 Text Alternatives: Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language Understanding Guideline 1.1

Guideline 1.2 Synchronized Media: Provide synchronized alternatives for synchronized media Understanding Guideline 1.2

Guideline 1.3 Adaptable: Create content that can be presented in different ways (for example [begin change]simpler layout [2094] [end change]) without losing information or structure Understanding Guideline 1.3

Guideline 1.4 Distinguishable: Make it easier for [begin change]users [2204] [end change] to see and hear content including separating foreground from background Understanding Guideline 1.4

Principle 2: Operable - User interface components and navigation must be operable

Guideline 2.1 Keyboard Accessible: Make all functionality available from a keyboard Understanding Guideline 2.1

Guideline 2.2 Enough Time: Provide users with disabilities enough time to read and use content Understanding Guideline 2.2

Guideline 2.3 Seizures: Do not design content in a way that is known to cause seizures Understanding Guideline 2.3

Guideline 2.4 Navigable: Provide ways to help users with disabilities navigate, find content and determine where they are Understanding Guideline 2.4

Principle 3: Understandable - Information and the operation of user interface must be understandable

Guideline 3.1 Readable: Make text content readable and understandable Understanding Guideline 3.1