UX Glossary · W
WCAG
Also: Web Content Accessibility Guidelines
The Web Content Accessibility Guidelines: the testable standard nearly every accessibility law refers to.
WCAG is the accessibility standard published by the W3C’s Web Accessibility Initiative. WCAG 2.0 arrived in 2008, 2.1 in 2018 and 2.2 in 2023. Version 3 is in development and is years from being a requirement.
Structure
Four principles, remembered as POUR:
- Perceivable: users can perceive the content
- Operable: users can operate the interface
- Understandable: content and behaviour are comprehensible
- Robust: it works with assistive technologies
Under these sit success criteria at three levels. A is the minimum, AA is what legislation and contracts almost always require, AAA is aspirational and not expected across a whole site.
The criteria that come up most
1.4.3 contrast of at least 4.5:1 for normal text. 1.4.11 contrast of 3:1 for interface components. 2.1.1 everything operable by keyboard. 2.4.7 focus visible. 1.3.1 structure conveyed programmatically, which is what headings and labels are for. 2.5.8, added in 2.2, target size of at least 24 by 24 pixels.
Why it is now commercial rather than optional
The European Accessibility Act applies from 28 June 2025, and the harmonised standard EN 301 549 references WCAG. German public bodies fall under BITV 2.0. Accessibility has become a procurement requirement rather than a matter of conscience.
In practice
Roughly half of common failures are caught by automated tools. The other half, focus order, label quality, sensible headings, needs a person.