Web Content Accessibility Guidelines (WCAG) are a recommendation published by the Web Accessibility Initiative group at the W3C. They outline a set of guidelines for making content accessible primarily for people with disabilities but also for limited-resource devices such as mobile phones.
WCAG 2.0 which superseded WCAG 1.0 was published as a W3C Recommendation on 11 December 2008. It consists of 12 guidelines organized under 4 principles (perceivable, operable, understandable, and robust) and each guideline has testable success criteria.
WCAG uses three levels of conformance:
- Priority 1: Web developers must satisfy these requirements, otherwise it will be impossible for one or more groups to access the Web content. Conformance to this level is described as A.
- Priority 2: Web developers should satisfy these requirements, otherwise some groups will find it difficult to access the Web content. Conformance to this level is described as AA or Double-A.
- Priority 3: Web developers may satisfy these requirements, in order to make it easier for some groups to access the Web content. Conformance to this level is described as AAA or Triple-A.
- WCAG on Wikipedia