What is usability?

Haven't you ever left a web site without having found what you were seeking?

At that moment, you discovered that it is not enough to visit a site to understand it. Just as it is not enough to buy a software to know how it works. Because they must also be designed in order to be easy to use! This is called: Usability or Ergonomics.

Definition of Usability

The usability is the capacity of an object to be easy to use by a given person to carry out the task for which it has been designed.

The usability concept encompasses:

  • Performance of task realization
  • Satisfaction provided by the use of the object
  • Ease of learning

This feature is related to any type of instrument designed to help the human being in its work. We are interested here in his application to data-processing tools, i.e. software and web sites.

Utility and Usability

Who never felt this feeling of frustration not to be able to use a software fully, because he doesn't know how to use of it?

Who didn't ever give up his search lost in a web site too complex or wearied of waiting the pages loading?

There is no doubt that software and web sites are useful, but they are not always easily usable...

In a general way, the use of an instrument is characterized according to two dimensions: Utility and Usability.

  • Utility is the capacity of the object to facilitate the realization of a human activity.
  • Usability represents the facility of use of the object.
Usability problem caricature
A typical problem of usability

An example: the scuba

Let us consider two objects dedicated to a similar use: the scuba and the diving suit. They concern the same utility: to allow to move under water.

However, the diving suit, because of its weight and its permanent connection with the source of air, is less usable than the scuba which offers greater autonomy.

The divers quickly understood it: since the scuba has been invented, the diving suit is almost not used any more. The tool with the greatest usability has been selected.