Web accessibility covers the practice of building web interfaces that work for users with disabilities — screen readers, keyboard-only navigation, low vision, color blindness, motor impairments, cognitive differences. Most countries now have legal frameworks (WCAG 2.2 in the US and EU, the European Accessibility Act in 2025) that make accessibility a compliance requirement, not just an ethical one.
The technical core is straightforward: semantic HTML, proper ARIA when semantic HTML doesn't cover the case, keyboard navigation, focus management, color contrast, and screen-reader testing with NVDA, JAWS, or VoiceOver. Courses cover all of the above plus the testing methodology that catches issues before users hit them — axe-core, Lighthouse, manual screen-reader walkthroughs.