ABSTRACT
The concept of usability is regarded by many as a milestone in the history of computer system design, specifically the design and evaluation of user interfaces. Since the term entered common usage in the early 1980’s, the consideration of usability has greatly impacted on the way in which many interactive systems are developed. Usability compels designers to think from the very beginning about end-users. Therefore, it has contributed to the evolution, from the traditional topdown design approach (all requirements were specified in the planning phase and then developed by stepwise refinements) to a more iterative-design approach (evaluation and implementation are closely linked, user input at key stages, and ongoing requirements definition and system specification).
