application or an "app", is computer software designed to help the user to perform specific tasks
Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with documents.
Questions having the application tag regards the User Experience of applications in general
Reference: http://en.wikipedia.org/wiki/Application_software