If you’ve just heard about usability, you need to start with the basics. The definition; how, when, and where can you improve it? Why should you care?

Usability can be defined in many different ways and can be seen as vast complex field of studies; it mainly represents a user’s ease to perform a function efficiently. Helen Sharp and Jakob Nielsen, among the well-known and respected gurus of interaction, define usability as:

“… effectiveness, ease of use, and satisfaction…” Helen Sharp

“… a quality attribute that assesses how easy user interfaces are to use.” Jakob Nielsen

Ben Shneiderman, a man of equal stature, and Nielsen further go on to divide usability into five factors that fit into the categories of efficiency, effectiveness and satisfaction. The category of efficiency relates to the speed of performance and the time it takes for a user to learn how to use the function; whereas effectiveness relates to the memorability and rate of errors (van Welie et.al, 1999). Such an approach reflects the ‘user and task dependent’ nature of usability as well as relating it to “how well the user is able to accomplish what they set out to do, how efficiently the user can do this, and how satisfied the user is during and after the process” (Whitehead 2006).

To get you started, check out this overview that covers the basic questions by Jakob Nielsen. Usability 101: Definition and Fundamentals – What, Why, How Jakob Nielsens Alertbox.

Example of bad usability design from theletter.co.uk

Example of bad usability design from theletter.co.uk