WCAG

The Web Content Accessibility Guidelines (WCAG) are the international digital accessibility recommendations published by the W3C. They define the technical and editorial criteria that web content must comply with to be accessible to people with disabilities. Organised according to four principles (Perceivable, Operable, Understandable, Robust), they are structured into three levels of conformity: A, AA and AAA.

Level A covers the basic criteria without which some users cannot access the content at all. Level AA is the level recommended for most services: it is required by the majority of regulations (RGAA, ADA, EN 301 549). Level AAA is the most demanding and is generally not achievable for an entire site: some AAA criteria are contradictory with each other for different audiences.

In design, the most impactful criteria are: colour contrast (minimum 4.5:1 for body text at AA), the size of clickable areas (44x44px minimum recommended), the legibility of keyboard focus (visible without extra CSS), the absence of information conveyed by colour alone, and the consistency of navigation across pages. These criteria directly influence the choices of palette, typography and layout.

The WCAG were designed mainly for the web, but their principles also apply to mobile applications. Specific adaptations exist: the platform guidelines (Apple Accessibility, Android Accessibility) apply the WCAG principles in the touch and mobile context. The EN 301 549 standard, adopted within the European framework, extends the accessibility requirements to software and mobile applications.

You distinguish automated tests (tools such as axe, WAVE or Lighthouse that detect around 30 to 40% of problems) from manual tests (keyboard navigation, screen reading with NVDA or VoiceOver, contrast checking). Tests with real users with disabilities are the most reliable method but also the most costly. In practice, you start with automated tests to identify the obvious problems, then complete them with targeted manual tests.