From Computer Science Wiki
System Fundamentals[1]

In software engineering, usability is the degree to which a software can be used by specified consumers to achieve quantified objectives with effectiveness, efficiency, and satisfaction in a quantified context of use [2].

Any discussion of usability must include the idea of ergonomics and accessibility.

Do I understand this?[edit]

You should be able to close your eyes and recite from memory this idea of usable and usability. However, I hope you take a moment to think more deeply about this idea. From this article, we learn usability might be decomposed into:

The definition of usability in the ISO 9241 standard is:

"The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency, and satisfaction in a specified context of use"[3]

This definition can be expanded, and made more comprehensive, by including five characteristics which must be met for the users of a product:

  • Effective
  • Efficient
  • Engaging
  • Error Tolerant
  • Easy to Learn


  • Define the term usability.


The circumstances that form the setting for an event, statement, or idea, and in terms of which it can be fully understood and assessed.

Give the precise meaning of a word, phrase, concept or physical quantity.