Publication February 28, 2013
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W3C recommendations from December 11, 2008
Check out fix list for this document, which may contain regulatory corrections.
This document also exists in alternative formats presented in the Alternative Versions section of the Web Content Accessibility Guidelines (WCAG).
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Web Content Accessibility Guidelines (WCAG)
Criteria for implementing WCAG recommendations
Status of this document
This section describes the status of this document at the time of its publication. Later this document may be replaced by other documents. A list of current W3C publications and the latest versions of this guide can be found in the W3C technical reports list at http: //
This document has been reviewed by W3C members, software developers, other groups and W3C members, and is endorsed by the Director as a recommendation to W3C. This Guide is an approved document that can be used as a reference or quoted in other documents. The role of W3C in preparing recommendations is to draw attention to these guidelines and to promote its widespread use. Such activities are aimed at improving the functionality and compatibility of web resources.
The working group recommends sending all comments only through the appropriate online form. If this is not possible, comments can be sent by e-mail. Public-comments-wcag20 @
This document was created as part of the W3C Web Accessibility Initiative (WAI). The objectives of the WCAG working group are described in the Bylaws, and their work is part of the WAI Technical activities.
When creating this document, the group was guided by the W3C Patent Strategy of February 5, 2004. The W3C maintains an open list of all patented inventions made in connection with the work of the group; This page also contains patent disclosure instructions. A subject who has valid knowledge of a patent, which, in the opinion of the subject, contains essential features of the invention, must disclose this information in accordance with Section 6 of the W3C Patent Strategy.
- WCAG Guide Levels
- 1. Appendix A: Glossary (Regulatory Section)
- 2. Appendix B: Acknowledgments
- 3. Appendix C: References
This section is informational.
Web Content Accessibility Guidelines (WCAG)
Although the provisions of the Guide take into account a wide range of restrictions and problems, they cannot describe the needs of people with all types, degrees and combinations of restrictions. Compliance with the principles outlined in the Guidelines will make web content more accessible to older users, whose abilities change with age, and in some cases will facilitate the use of content by other users.
Web accessibility depends not only on the availability of content, but also on the availability of web browsers and other custom components. An important role is also played by site development tools and content. You can get a general idea of how web development and user interaction components affect accessibility by reading the following documents:
WCAG Guide Levels
The WCAG document is intended for review and use by both organizations and individuals. Among the target audience of the document are the following groups: web developers and designers, management representatives, procurement agents, teachers and students. Within the Guidelines for different groups of the target audience, there are several types of instructions, including: principles, guidelines, tested performance criteria, a large collection of descriptions of minimally sufficient and recommended methods, documentation on common errors, containing examples, links, and program code.
Principles. The basis of web accessibility are four principles: perceptibility, controllability, clarity and reliability. (See also the explanations for the four principles of general accessibility).
Provisions. The principles are embodied in 12 positions. They represent the main goals that content authors should strive for in order to make content more accessible to users with different disabilities. The implementation of these provisions cannot be verified, but they set the general framework and define the regulatory requirements for the criteria for the implementation and optimal use of technology.
Performance criteria. For each position are given verifiable criteria for its successful implementation. Criteria allow using WCAG
Sufficient and recommendatory techniques. For every position and every criterion of successful WCAG implementation
All four levels of the Guide (principles, provisions, performance criteria, sufficient and recommendatory techniques) give an idea of how to make web content more accessible. We encourage content authors to familiarize themselves with all sections of the Guide, including recommendatory methodologies, in order to meet the needs of the widest possible user base.
It should be noted that even content that meets the requirements of accessibility at the highest level (AAA) will not be available absolutely for all users with all types, degrees, and combinations of disability. This is especially true for users with disabilities in the cognitive and speech areas, as well as in the field of learning difficulties. We urge content authors to take into account the whole range of methodologies, including recommendation methods, to seek additional recommendations and use best practices to achieve the highest possible level of accessibility of web content to their target audience. Using metadata can help your users find content that best meets their needs.
WCAG Accompanying Documents
WCAG Master Document
How to meet WCAG requirements
Read the Web Content Accessibility Guidelines (WCAG) overview for information on WCAG supporting materials.
Important WCAG Terms
It is important to note that in this standard the term “web page” has a wider meaning than just a static HTML page. It includes dynamic web pages, including “pages,” which are entire virtual interactive communities. The term “web page” also refers to interactive video, creating a presence effect, placed on a separate URI-address. For details, see What is a “web page”.
Some of the criteria for the Guidelines require the content (or parts of it) to be “programmable”. This means that the content must be presented in such a way that user applications (including assistive technologies) can extract and present information in a form different from the original. For details, see What is software defined.
The use of technology that supports accessibility means the following: a certain technology interacts with assistive technologies and special features of operating systems, browsers and other user applications. Technological capabilities assume WCAG criteria
The definition of “maintaining accessibility” is given in Appendix A: Glossary of this Guide. For details, see Explaining maintaining availability.
This section is normative.
Principle 1. Perceptibility: information and components of the user interface should be presented only in the form that users can perceive.
Controls, input information. If non-text content is a control or a field for inputting user information, then it has a name describing its purpose. (See Regulation
Time-limited media content. If non-text content is presented in the form of media content, limited in time, its text version provides, at a minimum, a brief description of this non-text content. (See Regulation
Test. If non-text content is a test or exercise that cannot be presented as text, then the alternative text version provides at least a brief description of this non-text content.
Sensory perception. If non-textual content is intended to create a specific sensory perception, then the text version, at a minimum, provides a brief description of this non-textual content.
Captcha If the goal of non-text content is confirmation that the person (and not the computer) is accessing the content, then a text version is available to the user that identifies and describes the purpose of this non-text content. In addition, an alternative form of captcha is provided, which uses alternative ways of presenting information available for other types of perception for users with various types of disabilities.
Design, formatting, invisibility. If non-textual content is used only for the purpose of formatting, visual formatting, or is completely invisible to users, then it should be implemented in such a way that assistive technologies can ignore it.