Web Content Accessibility Guidelines (WCAG)

Contents: General information.

The WCAG is an international standard for the accessible design of all information on a website or web application, including text, images, forms, audio and video. Developed by the World Wide Web Consortium (W3C), the WCAG are based on four core principles designed to ensure that web content is accessible. These principles are not only reflected in the BITV but also form the basis of EN 301 549.

The four principles of accessibility

1. Perceivability: Information and user interface components must be presented to users in such a way that they can be perceived (e.g. through text alternatives for non-text content, subtitles for videos, sufficient contrast).
2. Operability: Elements of the user interface and navigation must be operable (e.g. keyboard accessibility, sufficient time for operation, avoidance of flickering content).
3. Understandability: Information and the operation of user interface must be understandable (e.g. legible and understandable text, predictable navigation, guidance in the event of errors).
4. Robustness: Content must be robust enough to be reliably interpreted by a wide range of user agents (web browsers, assistive technologies) and remain compatible with future technologies.

If any of these principles are not met, users with impairments, chronic or mental illnesses will be unable to use the web.

For each of these principles, there is a list of guidelines that address that particular principle, provide a framework for it and set out the objectives that must be met in order to make content accessible. For each guideline, in turn, there are testable success criteria that describe precisely what must be achieved to comply with the standard. Finally, implementation techniques are documented for each guideline and each success criterion.