Application

An application is software for computers to help users specific task. On all computers, Linux, Windows and OS X, standalone programs have been known as Applications (or Apps).

In layman's terms, apps are the pieces of software that build up an operating system. For instance, a Mac™ would be very limited useless without any web browsers, text/image/audio/video editors/viewers, games, instant messengers, directories, mail readers, etc., especially without the Finder which lets you control your handle, preview, and in the cases of picture clippings and text clippings, read files.