Usability Evaluation: Principles, Heuristics, and Testing Questions

Judging whether an interface is usable, both analytically and empirically. Covers the foundational rules of usable interfaces (Nielsen's heuristics, affordances, feedback and system-status visibility, error prevention, consistency, cognitive load) applied through heuristic evaluation, plus moderated and unmoderated usability tests, task-based protocols, and A/B and preference testing. Includes when to test, writing tasks that avoid leading users, interpreting findings, and validating a solution before and after launch. Distinct from generative research in that it measures an existing design against usability criteria.