Web Content Accessibility Guidelines
The WCAG 2.0 is maintained by the WCAG Working Group – made up of W3C Members and other interested parties. Version 1.0 of the WCAG was first published in 1999 and WCAG 2.0 was published in 2008. The stability and widespread deployment of W3C standards is intended to enhance the functionality and universality of the web. While the WCAG applies to web based content such as HTML pages, SVG, Flash, PDF, Silverlight, mobile websites and other web technologies — the standards can be applied to other technologies such as software and native mobile apps. Non-normative documents have been provided to assist people in applying WCAG to non-web ICT and applying CAG and other WAI standards to mobile technologies.
There are a total of 12 accessibility guidelines organized under 4 principles of accessible design. Each guideline contains success criteria at different levels of accessibility that explain how the guideline applies in typical content development scenarios.
It is worth noting that the WCAG are meant to provide general guidance on implementing web accessibility. The guidelines themselves acknowledge that real world implementation strategy will vary from instance to instance. In terms of real world application this means that conformance with the WCAG must be evaluated by whether the success criteria was met and the conformance requirements such as accessibility supported ways of using technology are provided. What is considered conformant in one environment may not necessarily be conformant in another environment depending on the user agent and technologies used. This constraint applies to not only the WCAG but all standards and legislation that reference it, including Section 508, the Common Look and Feel requirements, and the Disability Discrimination Act. The WCAG working group provides guidance documents such as sufficient techniques known to meet success criteria and be accessibility supported and known failures which are techniques that are known to fail success criteria. Keep in mind however that just because a failure technique exists there may be other ways to meet the success criteria. In addition, just because a sufficient technique exists does not mean that a sufficient technique must be used to meet a success criteria — other techniques may be used to meet the success criteria.
WCAG 2.0 Levels
The WCAG 2.0 requirements are broken up into three levels:
Level A – This level defines the lowest or minimum level of accessibility. Many groups of users with disabilities will find it very difficult or impossible to access information in the document. Satisfying these success criteria is the minimum set of requirements.
Level AA – This level defines a higher level of accessibility. One or more groups will find it difficult to access information in the document. Satisfying these success criteria will remove significant barriers to accessing web content.
Level AAA – A web content developer may satisfy these highest level of success criteria. Satisfying these criteria will enhance the user experience for individuals with disabilities. Not all Level AAA success criteria can be addressed for all types of content.
Web Accessibility Standards generally contain the WCAG 2.0 Level A and AA success criteria and conformance requirements. This structure is similar to Section 508 requirements, the CLF requirements, and Equality Act of 2010 guidance.