The first set of formal guidelines for identifying how to develop accessible web content was the Web Content Accessibility Guidelines  (WCAG), developed through the World Wide Web Consortium's (W3C's) Web Accessibility Initiative (WAI™). WCAG 1.0 became an official W3C® Recommendation on May 5, 1999. The WCAG 1.0 lists fourteen guidelines and, additionally, provides a list of checkpoints for each guideline. There are a total of sixty-five checkpoints. Each checkpoint has been assigned a priority level (1-3), where Priority 1 checkpoints address barriers that make access impossible for one or more groups of users. Priority 2 and Priority 3 checkpoints address barriers that make access difficult and somewhat difficult, respectively.
With the passage of Section 508 of the Rehabilitation Act Amendments of 1998, the Architectural and Transportation Barriers Compliance Board (Access Board) was required to publish standards establishing a set of compliance criteria for the newly enacted legislation. The outcome of this process was the Electronic and Information Technology Accessibility Standards , which were published in the Federal Register on December 21, 2000. The Access Board standards are the only set of technology accessibility standards that have their basis in the law.
The Access Board standards cover the broad spectrum of electronic and information technology, including but not limited to web content. The section of the standards titled "Web-based intranet and internet information and applications" provides sixteen standards. These standards closely parallel the WCAG 1.0 Priority 1 checkpoints, but there are some differences. A thorough analysis of the differences was developed by Jim Thatcher, sponsored by the Association of Tech Act Projects. This side-by-side comparison  is available online.
Section 508 standards define the minimum level of web accessibility for websites developed or used by the federal government. Although in many instances the 508 standards and the WAI guidelines are identical or very similar, in general, WAI standards represent a higher level of accessibility. Regardless of which standards institutions use, they still must meet any obligations they have under the Americans with Disabilities Act and other legislation to provide access to specific individuals with disabilities who wish to access their website.
Both the WCAG 1.0 and Section 508 web accessibility standards are focused primarily on HTML accessibility. The W3C is currently at work on the Web Content Accessibility Guidelines 2.0 , a working draft that attempts to broaden the scope of the guidelines and to address accessibility as it applies to the full variety of web technologies, not just to HTML. As of the March 11, 2004, Working Draft, WCAG 2.0 summarizes web accessibility using four broad design principles:
- Content must be perceivable.
- Interface elements in the content must be operable.
- Content and controls must be understandable.
- Content must be robust enough to work with current and future technologies.
-  Web Content Accessibility Guidelines
-  Electronic and Information Technology Accessibility Standards
-  side-by-side comparison
-  Web Content Accessibility Guidelines 2.0