A Usability view of the Applications defined.
Finding the common parts that make the applications easy to use, with a consitent user interface, where the applications work in an intuitive manner.
Usability is critical to the successful adoption of any application. When information and interfaces are presented in a clear, consistent and coherent manner, users can focus on the task at hand, instead of spending time and energy trying to make the application work.
Usability ensures that an application works the way it should, both in terms of technological effectiveness and user comfort.