Which set of web accessibility standards or guidelines should I comply with?
Web accessibility is comprehensively covered by the World Wide Web Consortium (W3C) in their Web Content Accessibility Guidelines (WCAG), which includes guidelines and checkpoints (called success criteria). There have been multiple revisions of WCAG. Most laws, policies, and legal settlements or resolutions identify either WCAG 2.1 or WCAG 2.0 Level AA as the standard by which accessibility is measured. Level AA refers to the middle of three conformance levels (A, AA, and AAA). In order to conform with WCAG at Level AA, a website or product must meet all Level A and AA success criteria.
Websites created or used by United States federal agencies are required by Section 508 of the Rehabilitation Act of 1973, as amended in 1998, and in 2017, to meet Information and Communications Technology accessibility Standards for web pages. The amended Section 508 guidelines went into effect In January of 2018, and these incorporate WCAG 2.0 by reference.
Many states and educational entities have adopted one or both of these standards or guidelines.
Check to see if your organization is covered by a Federal or state law, policy, or set of web accessibility standards or guidelines. If not, determine which set of standards best meets your needs and the needs of your organization. Setting the bar as high as possible may reduce the likelihood that you will have to retrofit your site later in response to an individual's need for improved access.