What are the four WCAG principles and the conformance levels?
Assesses fundamental understanding of Web Accessibility conventions, runtime behavior, and memory/performance considerations.
Hiring managers look for precision, avoidance of ambiguous jargon, and ability to explain trade-offs under real production conditions.
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.
Candidate Response Strategy & Interview Tips
- Start with a concise one-sentence summary: Deliver a direct, confident answer first before expanding into nuances.
- Demonstrate real-world trade-offs: Discuss where this approach excels and when you would avoid it in production systems.
- Discuss complexity & edge cases: Proactively explain time/space complexity or boundary conditions (null values, scale limits).
- Prepare for interviewer follow-ups: Technical hiring panels frequently probe deeper into concurrency, backward compatibility, or alternative libraries.