Web Content Accessibility Guidelines
The Web Content Accessibility Guidelines (WCAG) are part of a series published by the Web Accessibility Initiative (WAI) of the World Wide Web Consortium (W3C), the main international standards organization for the Internet. They are a set of recommendations for improving web accessibility, primarily for people with disabilities—but also for all user agents, including highly limited devices, such as mobile phones.
Source: Wikipedia — Web Content Accessibility Guidelines (CC BY-SA 4.0)