Answer
Usability analysis helps determine the user-friendliness of the system being developed. This is important because it is the user-friendliness of a system that defines how much the actual users love or hate a system. However sophisticated, comprehensive and powerful a system be, if the users cannot use it with ease and are annoyed by it, the system‘s purpose shall not be met.
Because of this many large organizations have special arrangement to test usability of the systems by the users who are not aware of the other details or developmental activities but are just supposed to try to use the system and find its shortcomings.
The major criteria that help measure the usability of a system are:
Ease of learning: how much time and effort it takes for a new person to learn to use the system with ease.
Ease of use: how quickly a particular activity can be performed. If there are too many steps, too many clicks or too many screens, the system will not be user-friendly. Moreover, proper use of input tools such as keyboard, mouse and others along with output tools is necessary for ease of use.
Overall satisfaction: it is always desirable to have the users favorably pleased and happy with the system.