Web Accessibility Interview Questions and Answers

WCAG is organised around four principles known as POUR. Perceivable means information must be available to the senses, for example text alternatives for images, captions for video, sufficient colour contrast and content that works when zoomed. Operable means the interface must work without a mouse, with full keyboard access, visible focus, enough time to complete tasks, no content flashing more than three times per second, and touch targets large enough. Understandable means text should be readable, the interface should behave predictably, and users should get help avoiding and correcting errors. Robust means content should work with current and future assistive technologies, which in practice means valid semantic markup and correct ARIA.

Each principle has testable success criteria at three levels: A as the minimum, AA as the common legal target, and AAA as enhanced. Most accessibility laws reference WCAG 2.1 or 2.2 AA.

Semantic HTML uses elements that describe meaning: header, nav, main, section, article, aside, footer, button, label, table and ul. Assistive technologies and browsers derive roles, names, states and keyboard behaviour from these elements for free. A button announces itself as a button, is focusable and responds to Enter and Space. A styled div with an onclick does none of that without extra code, and the extra code is easy to get wrong.

Headings h1 to h6 form an outline that screen reader users navigate by, so use them for structure, not for font size. Landmarks let users jump between regions. Lists group related items, and tables with th and scope expose relationships.

Semantic markup is also better for SEO, easier to style and more robust than ARIA. The first rule of ARIA is not to use ARIA when a native element already does the job. Incorrect ARIA is often worse than none, because it overrides correct native semantics.