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This section is informative.

You are reading the Web Content Accessibility Guidelines (WCAG) 2.0. This is one of several documents that define and explain the requirements for making Web-based information and applications accessible to a wide range of people with disabilities, including blindness and low vision, deafness and hearing loss, learning difficulties, cognitive limitations, limited movement, speech difficulties, and others. Following these guidelines will also make your Web content more accessible to the vast majority of users, including older users. It will also enable people to access Web content using many different devices - including a wide variety of assistive technologies.

WCAG 2.0 covers a wide range of issues and recommendations for making Web content more accessible. In general, however, the guidelines do not include standard usability recommendations except where they have specific impact on accessibility.

WCAG 2.0 includes:

The Four Principles of Accessibility

The four principles of accessibility are as follows:

  1. Content must be perceivable to each user.

  2. User interface components in the content must be operable by each user.

  3. Content and controls must be understandable to each user.

  4. Content should be robust enough to work with current and future user agents (including assistive technologies)

These four principles lay the foundation necessary for anyone to access and use Web content. WCAG 2.0 offers information about how to increase the ability of people with disabilities to perceive, operate, and understand Web content. Under each principle there is a list of guidelines that address the principle. Under each guideline there are success criteria used to evaluate conformance to this standard for that guideline. The success criteria are written as statements that will be either true or false when specific Web content is tested against the success criteria. The success criteria are grouped into three levels of conformance each representing a higher level of accessibility for that guideline. (For more information about conformance, see the section titled Conformance , below.)

The principles, guidelines, and success criteria represent concepts that apply to all Web-based content. They address accessibility issues and needs, regardless of the technology used. They are not specific to HTML, XML, or any other technology. This approach makes it possible to apply WCAG 2.0 to a variety of situations and technologies, including those that do not yet exist.

The principles and guidelines give direction and guidance to Web authors. The success criteria are written as true/false statements so that they can be used in determining conformance. Only the success criteria are testable.

Success criteria should be interpreted in the context of the intention expressed in the guideline to which they belong. Likewise, each guideline should be understood in the context of the principle under which it appears.

Related Documents

In addition to WCAG 2.0 (this document) there are a number of related support documents that provide additional information and examples. These other documents are informative only and do not define conformance to WCAG 2.0. Only this document (WCAG 2.0) is normative. That is, only this document can be used for determining conformance to these guidelines. Readers should consult WCAG 2.0 in order to determine the exact wording of the guidelines and success criteria and for information about documenting conformance.

The other informative documents in this set are provided to help readers understand WCAG 2.0 and how to produce conforming content. These informative documents are written for different audiences, including but not limited to:

Currently, these informative documents include:

The Working Group plans to publish a number of other technology-specific Techniques documents and encourages development of techniques documents that show how to meet WCAG 2.0 using non-W3C technologies. Please visit the Working Group home page for a complete list of these and other informative documents related to WCAG 2.0.

Every attempt has been made to make WCAG 2.0 and the related documents listed above as readable and usable as possible while still retaining the accuracy and clarity needed in a technical specification. Sometimes technical terms are needed for clarity or testability. In these cases, the terms are defined in Appendix A Glossary . The Working Group recognizes that readers who are new to accessibility may need or want additional information. For these readers, the work of the Education and Outreach Working Group of the Web Accessibility Initiative is highly recommended. The articles called Getting Started: Making a Web Site Accessible and How People with Disabilities Use the Web are especially useful.

Authoring tools

A large part of Web content is created using authoring tools. These tools often determine how Web content is implemented, either by making authoring decisions directly or by limiting the choices available to the author. As a result, authoring tools will play an important role in creating Web content that conforms to the Web Content Accessibility Guidelines. At the same time, we recommend that all authors become familiar with the Guidelines because this will help in creating accessible content and coverage of the Guidelines may vary between tools.

Developers of authoring tools can help to make their tools more aware of the Web Content Accessibility Guidelines by following the Authoring Tool Accessibility Guidelines. We encourage users and purchasers of authoring tools to consider conformance to the Authoring Tool Accessibility Guidelines as a criterion when selecting tools.

Editorial Note: The Authoring Tool Accessibility Guidelines Working Group has published Working Drafts of ATAG 2.0. The above references will need to be updated as ATAG 2.0 moves through recommendation track.