The Web Content Accessibility Guidelines (WCAG) are the internationally recognized standard for making web content accessible to people with disabilities. Published by the W3C, they define testable criteria for visual design, interaction design, and content structure.
Who WCAG Protects
WCAG criteria address a wide range of disabilities: visual impairments (low vision, color blindness, blindness), motor impairments (inability to use a mouse), cognitive disabilities (difficulty processing complex layouts), and hearing impairments (for audio/video content). Color-related criteria primarily serve users with visual impairments.
The Three Levels
WCAG defines three conformance levels. Level A is the bare minimum, covering the most critical barriers. Level AA is the standard target for most organizations and the level referenced by most accessibility laws. Level AAA is the highest standard, achievable for some content but often impractical as a blanket requirement.
Color-Specific Criteria
Several WCAG criteria directly involve color. Success Criterion 1.4.3 requires a contrast ratio of at least 4.5:1 for normal text (AA). SC 1.4.6 raises that to 7:1 (AAA). SC 1.4.1 says color cannot be the sole means of conveying information. SC 1.4.11 requires 3:1 contrast for UI components and graphical objects.
Legal Landscape
In the United States, the ADA has been interpreted by courts to apply to websites. The EU's European Accessibility Act requires WCAG 2.1 AA compliance. Canada, Australia, and many other countries have similar laws. Accessibility is not optional. It is a legal obligation for most commercial websites.