Web accessibility means that people with disabilities can use a website: read it with a screen reader, operate it with a keyboard alone, follow it with low vision or a cognitive disability, and understand video with captions. The reference standard is the Web Content Accessibility Guidelines (WCAG) published by the World Wide Web Consortium. Version 2.2 became the current recommendation in October 2023.
Four principles
WCAG groups its rules under four principles: content must be perceivable, operable, understandable and robust. In practice that means text alternatives for images, captions for video, enough colour contrast, everything reachable by keyboard, no content that flashes, clear headings and labels, and code that assistive technology can interpret. Each rule has a level: A, AA or AAA. Laws and contracts almost always refer to level AA.
The law in the United States
The Americans with Disabilities Act does not mention websites, but courts and the Department of Justice have treated the sites of businesses open to the public as covered by Title III. In April 2024 the Department of Justice issued a rule under Title II that requires state and local governments to meet WCAG 2.1 level AA, with deadlines in 2026 and 2027 depending on the size of the jurisdiction. Federal agencies have had to follow Section 508 of the Rehabilitation Act, which also points to WCAG, since 2018.
The law in the European Union
Public-sector websites in the EU have been covered by the Web Accessibility Directive since 2018. The European Accessibility Act extended obligations to private companies from 28 June 2025: online shops, banking, e-books, ticketing and telecom services must be accessible, and the technical yardstick is the standard EN 301 549, which incorporates WCAG.
Where to start
Most failures are simple. Run an automated checker such as the WAVE browser extension or the accessibility audit in Chrome’s developer tools, then test by hand: unplug the mouse and navigate with Tab and Enter, zoom the page to 200 percent, and try a screen reader such as NVDA, which is free. Fix missing alternative text, unlabeled form fields and low contrast first. Those three account for the majority of reported problems.