Also known as: ease of use
Usability is the degree to which a product or system can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use (ISO 9241-11).
Usability is not the same as user experience (UX). UX is broader, encompassing all aspects of a person's interaction with a product, including aesthetics, emotions, and brand perception. Usability is a measurable attribute of a system: can users actually accomplish what they set out to do?
The ISO 9241 standard breaks usability into three components:
- Effectiveness: can the user achieve their goals at all?
- Efficiency: how much effort, time and resources does it take?
- Satisfaction: how comfortable and pleasant is the experience?
Good usability matters most in safety-critical domains like aviation, medicine, and nuclear power, where usability failures can kill people. But it matters everywhere, poor usability wastes time, causes frustration, and excludes users with disabilities.
Related terms: User Experience, ISO 9241, Human-Centred Design
Discussed in:
- Chapter 1: Introduction: What Is Usability? (Introduction)
Also defined in: Textbook of Usability