Application software is all the computer software that causes a computer to perform useful tasks (compare with Computer viruses) beyond the running of the computer itself. A specific instance of such software is called a software application, application or app.

The term is used to contrast such software with system software, which manages and integrates a computer's capabilities but does not directly perform tasks that benefit the user. The system software serves the application, which in turn serves the user.

Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with documents. Applications may be bundled with the computer and its system software or published separately, and can be coded as university projects.

Application software applies the power of a particular computing platform or system software to a particular purpose.

Some applications are available in versions for several different platforms; others have narrower requirements and are thus called, for example, a Geography application for Windows or an Android application for education or Linux gaming. Sometimes a new and popular application arises which only runs on one platform, increasing the desirability of that platform. This is called a killer application.