Usability

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. It is a quality attribute and one of the eight top-level characteristics in the ISO/IEC 25010 quality model, alongside others such as performance efficiency and maintainability.

ISO/IEC 25010 decomposes usability into six sub-characteristics: appropriateness recognizability, whether users can tell the product fits their needs; learnability, how readily a new user builds a working mental model of it; operability, how easy it is to run and control; user error protection, how well it guards against mistakes; user interface aesthetics, how pleasing the interaction is; and accessibility, how well it serves users with the widest range of characteristics and capabilities.

Because it’s framed around the end user’s experience rather than a system’s internal qualities, usability is usually assessed through usability testing with real or representative users, rather than through the automated checks that suit attributes like performance or security.

References

• ISO/IEC (2023). ISO/IEC 25010:2023 — Systems and software Quality Requirements and Evaluation (SQuaRE) — Quality model.