When having a discussion about usability it is virtually impossible to do so without mentioning Jakob Nielsen. Nielsen is one of the worlds leading experts on usability and the founder of the “discount usability” movement. Nielsen describes interface usability as, “a quality attribute that assesses how easy user interfaces are to use” and goes on to explain that usability can be defined by five components:
Five Key Usability Components
- Learnability: The ease of which users grasp the ability to perform basis tasks.
- Efficiency: The speed at which users can complete tasks.
- Memorability: The ability for users to recall information and to re-establish proficiency.
- Errors: The number and severity of errors made.
- Satisfaction: The satisfaction derived from using the system and the extent to which requirements were met.
The authors of “Usability for the Web: Designing Web Sites That Work” explain that a usable system should have the appropriate functionality and be efficient to use. This efficiency can be, “a measure of time or actions required to correctly perform the functions that the user needs.
Author Steve Krug suggests that usability means, “making sure that something works well: that a person of average (or even below average) ability and experience can use the thing – whether it’s a Web site, a fighter jet, or a revolving door – for its intended purpose without getting hopelessly frustrated”
So what is website usability? A usable website will allow the user to accomplish their tasks quickly, efficiently and easily, without confusion or frustration. Furthermore, designing for good usability is about understanding the processes, capabilities and preferences of the users instead of relying on the perspective of the programmers alone. This prevents programmers from designing systems according to their personal interpretation.