What Is WCAG?
Almost every accessibility requirement in the US points back to one document. WCAG is that document, and the version a law names decides what “accessible” means for you. This is general information, not legal advice.
Quick Answer
WCAG (Web Content Accessibility Guidelines) is the World Wide Web Consortium's standard for making web content accessible to people with disabilities. It is organized as testable success criteria at three levels: A, AA and AAA. The current version, WCAG 2.2, became a W3C Recommendation on 5 October 2023 and has 55 success criteria at Level A and AA combined. US law references specific versions: the ADA Title II web rule names WCAG 2.1 AA; Section 508 names WCAG 2.0 A and AA.
Versions, levels and the four principles
WCAG has been revised in steps: 2.0, then 2.1, then 2.2. Each later version keeps the earlier criteria and adds new ones. W3C states that “the 2.0 and 2.1 success criteria are essentially the same in 2.2, with one exception”: 4.1.1 Parsing, which “is obsolete and removed from WCAG 2.2.” WCAG 2.2 added nine criteria, including 2.5.8 Target Size (Minimum) and 3.3.8 Accessible Authentication (Minimum) at Level AA. See What's new in WCAG 2.2.
Success criteria are grouped under four principles: content must be perceivable, operable, understandable and robust. Each criterion has a conformance level. Level A is the floor, Level AA is the level laws and contracts usually require, and Level AAA is the strictest. In WCAG 2.2 there are 31 Level A, 24 Level AA and 31 Level AAA criteria in force, so “WCAG 2.2 AA” means the 55 A and AA criteria together. Our WCAG 2.2 checklist lists all 55 with a plain-language test for each.
Automated tools find only part of it
Which version applies to you
The version depends on who you are. The Department of Justice's 2024 rule for state and local governments sets “WCAG Version 2.1, Level AA” as the technical standard (see our guide to the Title II web rule). The revised Section 508 Standards for federal agencies require electronic content to conform to WCAG 2.0 Level A and AA. For businesses open to the public, DOJ's 2022 guidance names WCAG as helpful guidance but there is no regulation setting a version.
Because 2.2 keeps the 2.1 criteria (apart from the removed 4.1.1), building to WCAG 2.2 AA covers what 2.1 AA asks for. The practical differences are covered in WCAG 2.1 vs 2.2. To see how a page does against the automatable checks, run the accessibility checker.
Frequently Asked Questions
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