ISO Definition of Usability

The following definition is provided by the International Standards Organization (ISO):

Usability is the "effectiveness, efficiency and satisfaction with which a specified set of users can achieve a specified set of tasks in a particular environment."

The increased interest in the ease of use of computers has created rising expectations for the user interface. Usability is rapidly becoming recognised as a crucial element in the development lifecycle and the marketing mix. Now is the time to address usability and focus on user interface design.

"In the past, designers were constrained by what could be done; now designers can think about what should be done." (Eberts, 1994).