Recommendation from the W3C, which explains to developers and authors how to make Web content accessible to people with disabilities.
Web Content Accessibility Guidelines wcag are part of a series of Web accessibility guidelines published by the W3C's Web Accessibility Initiative wai. The current version is 2.1, which became a W3C Recommendation on 05 June 2018, content that conforms to WCAG 2.1 also conforms to wcag2.0.
They consist of a set of guidelines for making content accessible, primarily for disabled users, but also for all user agents, including highly limited devices, such as mobile phones.
The primary considerations for web content are Perceivable, Operable, Understandable, Robust, and Conformance. Within each category there are several guidelines and breakdown for 3 levels of compliance (A, AA, AAA).
The WCAG 2.0 overview from W3C can be found here.
