Abstract
This document, "Understanding WCAG 2.0," is an essential guide to understanding and using Web Content Accessibility Guidelines (WCAG) 2.0 [WCAG20]. It is part of a series of documents that support WCAG 2.0. Please note that the contents of this document are informative (they provide guidance), and not normative (they do not set requirements for conforming to WCAG 2.0). See Web Content Accessibility Guidelines (WCAG) Overview for an introduction to WCAG, supporting technical documents, and educational material.
WCAG 2.0 establishes a set of Success Criteria to define conformance to the WCAG 2.0 Guidelines. A Success Criterion is a testable statement that will be either true or false when applied to specific Web content. "Understanding WCAG 2.0" provides detailed information about each Success Criterion, including its intent, the key terms that are used in the Success Criterion, and how the Success Criteria in WCAG 2.0 help people with different types of disabilities. This document also provides examples of Web content that meet the success criterion using various Web technologies (for instance, HTML, CSS, XML), and common examples of Web content that does not meet the success criterion.
This document indicates specific techniques to meet each Success Criterion. Details for how to implement each technique are available in Techniques for WCAG 2.0, but "Understanding WCAG 2.0" provides the information about the relationship of each technique to the Success Criteria. Techniques are categorized by the level of support they provide for the Success Criteria. "Sufficient techniques" are sufficient to meet a particular Success Criterion (either by themselves or in combination with other techniques), while other techniques are advisory and therefore optional. None of the techniques are required to meet WCAG 2.0, although some may be the only known method if a particular technology is used. "Advisory techniques" are not sufficient to meet the Success Criteria on their own (because they are not testable or provide incomplete support) but it is encouraged that authors follow them when possible to provide enhanced accessibility. Another support category is "Common Failures", which describe authoring practices known to cause Web content not to conform to WCAG 2.0. Although failures provide advisory information about certain authoring practices, authors must avoid those practices in order to meet the WCAG 2.0 Success Criteria.
This document is part of a series of documents published by the W3C Web Accessibility Initiative (WAI) to support WCAG 2.0. This document was published as a Working Group Note at the same time WCAG 2.0 was published as a W3C Recommendation. Unlike WCAG 2.0, is expected that the information in Understanding WCAG 2.0 will be updated from time to time. See Web Content Accessibility Guidelines (WCAG) Overview for an introduction to WCAG, supporting technical documents, and educational material.
Status of This Document
This section describes the status of this document at the time of its
publication. Other documents may supersede this document. A list of current
W3C publications and the latest revision of this technical report can be
found in the W3C technical reports index at http://www.w3.org/TR/.
This is a Working Group Note "Understanding WCAG 2.0". The Web
Content Accessibility Guidelines Working Group considers this document
to be important for understanding the success criteria in the Web
Content Accessibility Guidelines (WCAG) 2.0 Recommendation. Please
note that the contents of this document are informative (they provide guidance),
and not normative (they do not set requirements for conforming to WCAG
2.0).
Understanding WCAG 2.0 was previously
published on 11 December 2008 as a Working
Group Note. This new version updates the support information
provided for WCAG 2.0. Note that WCAG 2.0 itself remains unchanged,
only the informative support materials have been updated. Primary
changes include addition of Flash techniques, and clarifications
based on input from the public and translators. The changes are highlighted
in the diff-marked
version.
The Working Group requests that any comments be made using the provided online
comment form. If this is not possible, comments can also be sent to public-comments-wcag20@w3.org.
The archives
for the public comments list are publicly available. Comments received
on this document may be addressed in future versions of this document,
or in another manner. The Working Group does not plan to make formal responses
to comments. Archives of the WCAG
WG mailing list discussions are publicly available, and future work
undertaken by the Working Group may address comments received on this document.
This document has been produced as part of the W3C Web
Accessibility Initiative (WAI). The goals of the WCAG Working Group
are discussed in the WCAG
Working Group charter. The WCAG Working Group is part of the WAI
Technical Activity.
Publication as a Working Group Note does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or obsoleted
by other documents at any time. It is inappropriate to cite this document
as other than work in progress.
This document was produced by a group operating under the 5 February 2004
W3C Patent Policy. W3C maintains a public
list of any patent disclosures made in connection with the deliverables
of the group; that page also includes instructions for disclosing a patent.
An individual who has actual knowledge of a patent which the individual
believes contains Essential
Claim(s) must disclose the information in accordance with section
6 of the W3C Patent Policy.