Terminology Definition Series: Usability

Blog Post created by FGarofalo-esristaff on Jul 22, 2014

As a side note, I figured I'd give a try to drafting a series of concise blog posts with definitions of terminology from the disciplines of UX, UCD, HCI (etc.)






  • Source: http://en.wikipedia.org/wiki/Usability
    • Usability is the ease of use and learnability of a human-made object.
  • Source: http://www.nngroup.com/articles/usability-101-introduction-to-usability
    • Usability is a quality attribute that assesses how easy user interfaces are to use. Usability is defined by 5 quality components:
      • Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design?
      • Efficiency: Once users have learned the design, how quickly can they perform tasks?
      • Memorability: When users return to the design after a period of not using it, how easily can they reestablish proficiency?
      • Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
      • Satisfaction: How pleasant is it to use the design?
  • Source: http://www.w3.org/2002/Talks/0104-usabilityprocess/slide3-0.html
    • Usability (ISO 9241 definition): The effectiveness, efficiency and satisfaction with which specified users achieve specified goals in particular environments.
      • effectiveness: the accuracy and completeness with which specified users can achieve specified goals in particular environments
      • efficiency: the resources expended in relation to the accuracy and completeness of goals achieved
      • satisfaction: the comfort and acceptability of the work system to its users and other people affected by its use

  • Source: Usability glossary | Usability Body of Knowledge
    • Usability is the degree to which something - software, hardware or anything else - is easy to use and a good fit for the people who use it.