Nielsen's 10 Usability Heuristics Foundational principles for evaluating and designing usable interfaces. Apply these as a review checklist and as design constraints from the start — not only as a post-hoc audit tool. --- 1. Visibility of System Status The design should always keep users informed about what is going on, through appropriate feedback within a reasonable amount of time. Users cannot make good decisions without knowing the current state of the system. Trust is built through clear, timely feedback. In practice: - Show loading states, progress indicators, and completion confirmatio…