Understanding WCAG 2.0
A guide to understanding and implementing Web Content Accessibility Guidelines 2.0
W3C Working Group Note 11 December 2008
- This version:
-
http://www.w3.org/TR/2008/NOTE-UNDERSTANDING-WCAG20-20081211/
- Latest version:
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http://www.w3.org/TR/UNDERSTANDING-WCAG20/
- Previous version:
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http://www.w3.org/TR/2008/WD-UNDERSTANDING-WCAG20-20081103/
- Editors:
- Ben Caldwell, Trace R&D Center, University of
Wisconsin-Madison
- Michael Cooper, W3C
- Loretta Guarino Reid, Google, Inc.
- Gregg Vanderheiden, Trace R&D Center, University of
Wisconsin-Madison
- Previous Editors:
- Wendy Chisholm (until July 2006 while at W3C)
- John Slatin (until June 2006 while at Accessibility Institute, University of Texas at
Austin)
This document is also available in these non-normative formats:
Copyright © 2008 W3C® (MIT, ERCIM, Keio), All Rights Reserved. W3C liability, trademark and document use rules apply.
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.