Foundations

What Is WCAG? The Web Content Accessibility Guidelines Explained

WCAG (Web Content Accessibility Guidelines) is a set of technical requirements for making websites, apps, and digital documents usable by people with disabilities — including people who are blind or low-vision, deaf or hard of hearing, have limited mobility, or have cognitive or learning disabilities. It's published by the World Wide Web Consortium (W3C), the same organization that standardizes HTML and CSS, through its Web Accessibility Initiative (WAI).

If you've ever seen a company claim its site is "WCAG 2.1 AA compliant," this is the document they're referring to.

Why WCAG exists

Around 16% of the world's population lives with a significant disability. Without deliberate design choices, ordinary web patterns quietly lock large numbers of people out: an image with no text description is invisible to a screen reader, a form field with no label is a guessing game for anyone who can't see its placement on the page, and text with poor color contrast disappears for millions of people with low vision.

WCAG exists to turn "please make your site accessible" — a vague, unenforceable request — into a specific, testable checklist. Instead of guessing what "accessible" means, a developer can check a page against SC 1.4.3 (Contrast Minimum) and get a yes-or-no answer: does the text have at least a 4.5:1 contrast ratio against its background, or doesn't it?

What WCAG actually covers

WCAG is organized into four top-level principles — content must be Perceivable, Operable, Understandable, and Robust (POUR) — each broken into guidelines, and each guideline broken into specific, testable success criteria. See The 4 POUR Principles for what each one means in practice.

The current version most organizations target is WCAG 2.2, published by the W3C in October 2023. It defines 55 success criteria at Levels A and AA combined (31 at Level A, 24 at Level AA) — the two conformance levels almost every legal and procurement standard actually requires. See Conformance Levels A, AA, and AAA Explained for what those levels mean, and WCAG Versions Explained for how 2.2 relates to the earlier 2.0 and 2.1 releases most legislation still cites by name.

Is WCAG itself a law?

No — WCAG is a technical standard, not a statute. But it's the standard that laws point to. The ADA, Section 508, and the EU's Web Accessibility Directive / European Accessibility Act don't write their own accessibility rules from scratch; they reference WCAG (usually 2.0 or 2.1 AA) as the bar a website has to clear. That's why "WCAG compliant" has become shorthand for "legally defensible," even though the guidelines themselves carry no legal force on their own.

How to actually use WCAG

Reading the raw W3C specification is a rough experience — it's written for standards bodies, not for the developer trying to fix a specific broken form field on a Tuesday afternoon. That's the gap this knowledge base is meant to close: every success criterion, every commonly-found violation, and every relevant legal standard gets a plain-English page here, cross-linked so you can go from "my scan flagged this" to "here's exactly what to change."

If you want to see where your own site stands against WCAG 2.2 today, AllyProof's free scanner checks any page in about 30 seconds — no signup required.

Common questions

What is WCAG?

The Web Content Accessibility Guidelines — a W3C technical standard defining how to make digital content usable by people with disabilities, including blind, low-vision, deaf, motor-impaired, and cognitively impaired users.

Who creates WCAG?

The World Wide Web Consortium (W3C), the international standards body for the web, through its Web Accessibility Initiative (WAI). It is a consensus standard, not a government regulation.

Why does WCAG matter?

It is the yardstick nearly every accessibility law and procurement rule points to. Meeting WCAG (usually 2.1 or 2.2 AA) is how organizations make content usable for everyone and demonstrate legal due diligence.