Web Content Accessibility Guidelines (WCAG)

WCAG 2 organizes its guidelines under four principles: content must be perceivable, operable, understandable, and robust. Each guideline has success criteria, and a page or document conforms at a level when it satisfies every criterion at that level and the levels below it.

Versions

• WCAG 1.0: W3C Recommendation, May 5, 1999. Superseded and no longer recommended for new implementation.
• WCAG 2.0: December 11, 2008.
• WCAG 2.1: June 5, 2018. The version adopted by the U.S. Department of Justice’s ADA Title II rule, at Level AA.
• WCAG 2.2: October 5, 2023. Also published as the international standard ISO/IEC 40500:2025.
• WCAG 3: W3C Accessibility Guidelines 3.0, in early draft.

Documents

Although WCAG is written for web content, it applies to documents published on the web, such as PDFs. The W3C publishes format-specific techniques, including PDF techniques such as PDF18 for setting a document’s title. The ADA Title II rule applies WCAG 2.1 Level AA to conventional electronic documents that are web content, subject to the rule’s exceptions.

Sources

• WCAG 2 Overview, W3C Web Accessibility Initiative. Retrieved September 24, 2026.
• Web Content Accessibility Guidelines (WCAG) 2.1, W3C Recommendation, 2018. Retrieved September 24, 2026.
• Web Content Accessibility Guidelines 1.0, W3C Recommendation, May 5, 1999. Retrieved September 24, 2026.
• PDF18: Specifying the document title using the Title entry in the document information dictionary of a PDF document, W3C Web Accessibility Initiative. Retrieved September 24, 2026.
• Fact Sheet: New Rule on the Accessibility of Web Content and Mobile Apps Provided by State and Local Governments, U.S. Department of Justice, ADA.gov. Retrieved September 24, 2026.