This document attempts to answer the questions many people have regarding why they should bother with Validating their web sites and tries to dispel a few common myths.

Read more at
http://validator.w3.org/docs/why.html#bignames

This document maps Section 508 Standards for Electronic and Information Technology, Subpart B – Technical Standards, Section 1194.22 (Web Criteria) into the Success Criteria and Sufficient Techniques for the Web Content Accessibility Guidelines 2.0. The basic factor that links the two standards is user need. The needs identified by the Section 508 Criteria must be satisfied by all web content or web technologies in order to satisfy Section 508. The threshold of satisfaction will be the equally effective access test required by Section 504, the nondiscrimination section of the Federal Rehabilitation Act (1973). Equally effective access to a document is access that enables equal timeliness and equal quality in a perceptual and operational mode that meets the user’s needs. Any lower threshold requires additional accommodation for the hosting organization.

Web Content Accessibility Guidelines (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 disabilities, photosensitivity and combinations of these. Following these guidelines will also often make your Web content more usable to users in general.

A guide to understanding and implementing Web Content Accessibility Guidelines 2.0

http://www.w3.org/TR/UNDERSTANDING-WCAG20/

A customizable quick reference to Web Content Accessibility Guidelines 2.0 requirements (success criteria) and techniques

http://www.w3.org/WAI/WCAG20/quickref/