What is Usability

The paper relates different approaches to usability based on the product, the user, ease-of-use, actual usage and the context of use; and proposes that usability should be defined as the ease of use and acceptability of a product for a particular class of users carrying out specific tasks in a specific environment. Criterion levels for measure- ments of attitude and user performance determine whether the design of the product is successful in achieving usability. Diagnostic evaluation of usability problems may be based on analysis of user interaction or comparison of product attributes with guidelines. 1. DEFINITIONS OF USABILITY The term usability was coined some 10 years ago in order to replace the term “user friendly” which by the early 1980s had acquired a host of undesirably vague and subjective connotations. However, in the intervening years, the word usability itself has become almost as devalued as the term it was intended to supplant. There are still many different approaches to making a product usable, and no accepted definition of the term usability. The definitions which have been used derive from a number of views of what usability is. Three of the views relate to how usability shoul