Usability is the ease by which a developer creates a more effective and efficient application. This article well-explains the term usability in mobile application development. How usability is imporatant in an application development life cycle and which things should be kept in mind in terms of usability is lucidly explained in this article.
Author has also suggested a reference book to get get into more detail. This article provides some essential and primary information about usability which can be helpful to improve efficiency of our application. It also provides some links to related imporant articles for further reference.
Providing an organized and simple approach about usability, this article can be useful to beginner designers.