Web Content Accessibility guidelines is must read guideline for webmasters and web developers. This guideline will help us, webmasters and web developers to create websites that not only can be access and reach by ordinary people, it is also for people with disabilities.
Web Content Accessibility is also for search engine optimization. By following Web Content Accessibility guideline, the contents not only can be access by ordinary people and people with disabilities, it is also create a contents that easily index by search engine robots and optimization tools.
Another guideline to be refer from US goverment.
Section 508 requires that Federal agencies' electronic and information technology is accessible to people with disabilities. IT Accessibility & Workforce Division, in the U.S. General Services Administration's Office of Governmentwide Policy, has been charged with the task of educating Federal employees and building the infrastructure necessary to support Section 508 implementation.