Web Content Accessibility Guidelines 2.0 (WCAG 2.0) covers a wide range
of recommendations for making Web content more accessible. Following
these guidelines will make content accessible to a wider range of people
with disabilities, including blindness and low vision, deafness and
hearing loss, learning disabilities, cognitive limitations, limited
movement, speech difficulties, photosensitivity and combinations of
these. Following these guidelines will also often make your Web content
more usable to users in general.
http://www.w3.org/TR/2008/CR-WCAG20-20080430/
www.peoplewho.org