Usability

How easily and effectively people can use a product to reach their goals, commonly judged by learnability, efficiency, memorability, errors, and satisfaction.

Why it matters

Usability is the floor of UX, not the ceiling — a product can be perfectly usable and still pointless, but it cannot be delightful and unusable. The five-part breakdown (learnability, efficiency, memorability, errors, satisfaction) is what makes it workable: 'this app is confusing' starts arguments, 'new users fail the second step' starts fixes. Measure it, or you are grading your own homework by feel.

The numbers

5 components in Nielsen's classic definition: learnability, efficiency, memorability, errors, satisfaction

Related terms

User-Centric Design
Generalist
Heuristic Evaluation
Primary Research
System Usability Scale (SUS)

Go deeper in Learn UX

Introduction to usability testing Usability Testing & Iteration
Plan a usability study Usability Testing & Iteration

On the checklists

UX Checklist Plan
Usability Study Planner Participants

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