Web accessibility is a set of guidelines for making websites usable for people with disabilities. These sets of guidelines, called Web Content Accessibility Guidelines (WCAG) have been compiled by the World Wide Web Consortium (W3C). You need to complete the WCAG requirements in order to have your website compliant.
Before even getting into the actual requirements and available solutions, one thing is crucial to understand: making your website accessible for people with disabilities is not a “nice thing to do”, it is required by law and enforced by compliance regulations.