Glossary A–ZLetter W
WCAG
The WCAG are the internationally used guidelines for accessible web content, setting out how texts, images, videos and controls must be designed so that people with disabilities can use them.
The abbreviation stands for “Web Content Accessibility Guidelines”; they are published by the W3C.
The guidelines group their requirements under four principles: perceivable, operable, understandable and robust. Each success criterion has a level, A, AA or AAA. A well-known example is the contrast ratio of at least 4.5 to 1 for normal text at level AA. The European standard EN 301 549 on accessible ICT refers to the WCAG for web content, and through it they feed into legal requirements.
The WCAG were not written specifically for screens, but many criteria can be applied: contrast, text size, subtitles, no information conveyed by colour alone, no rapid flashing. With touchscreens, the size and reach of controls are added. Whether a particular screen must be accessible by law depends on how it is used; the WCAG describe the benchmark, not the obligation.