Standards

WCAG

Also: Web Content Accessibility Guidelines

The Web Content Accessibility Guidelines, the W3C standard most accessibility laws cite. WCAG defines what makes web content perceivable, operable, understandable, and robust for people with disabilities.

The Web Content Accessibility Guidelines (WCAG) are produced by the W3C’s Web Accessibility Initiative (WAI). They are the most widely-adopted standard for digital accessibility, cited directly or by reference in nearly every major accessibility law worldwide. WCAG is what most engineers, designers, and auditors actually mean when they say “accessibility compliance.”

Versions in active use

Three WCAG versions are currently encountered in real contracts and audits:

  • WCAG 2.0 (2008) — still cited by older regulations including the original AODA Integrated Accessibility Standards Regulation and pre-2024 US Section 508 guidance.
  • WCAG 2.1 (2018) — added 17 success criteria covering mobile, low vision, and cognitive accessibility. This is the version EN 301 549 (and therefore the EAA) currently incorporates by reference.
  • WCAG 2.2 (October 2023) — adds nine more success criteria, mostly around focus visibility, drag operations, and accessible authentication.

WCAG 3.0 is in working-draft status. It is not suitable for citing in contracts yet, despite occasional marketing claims to the contrary.

Conformance levels

Each WCAG success criterion is assigned exactly one of three levels: A (absolute minimum), AA (the practical compliance floor), or AAA (highest, often impractical site-wide). Laws and procurement contracts almost always target Level AA. The W3C explicitly does not endorse partial compliance claims like “60% AA-compliant” — meeting “Level AA” requires passing every Level A and Level AA criterion.

What WCAG does and doesn’t cover

WCAG is intentionally tech-neutral. It applies to HTML, PDFs, mobile apps, ePub publications, and emerging formats. It deliberately stays away from:

  • Native operating-system UI (covered by Section 508 chapters 5-7, EN 301 549 chapters 5-12, and platform guidelines).
  • Hardware accessibility (Section 508 ch. 4, EN 301 549 ch. 5).
  • Cognitive-disability-specific design patterns (the WAI’s Cognitive Accessibility Task Force publishes supplementary guidance).

How to use WCAG in practice

Treat WCAG as a floor, not a ceiling. Automated tools detect at most 30–40 % of WCAG issues; the remainder requires manual testing with real assistive technology and, ideally, sessions with disabled users. Articles across this site repeatedly cite specific success criteria by their two-or-three-digit number (e.g. 2.4.3, 4.1.2) — those are direct references into WCAG’s machine-readable success-criterion list.