What is Accessibility (a11y)?
The practice of building web interfaces usable by people with disabilities, guided by WCAG standards and assistive technology support.
Definition
Web accessibility ensures interfaces work with screen readers (NVDA, JAWS, VoiceOver), keyboard-only navigation, voice control, and other assistive technologies. The WCAG 2.2 guidelines define testable success criteria across three levels (A, AA, AAA); level AA is the common legal benchmark under the ADA, the European Accessibility Act, and Section 508. Practical foundations include semantic HTML, sufficient color contrast (4.5:1 for body text), visible focus states, and correct ARIA usage. Tooling like axe-core, Lighthouse, and eslint-plugin-jsx-a11y catches roughly a third of issues automatically; the rest require manual keyboard and screen-reader testing.