An app or application (also known as a program) is a piece of software, effectively, a bit of code that has been compiled to run on a device. That device may be any computing device: a desktop computer, mobile device, server, or an embedded piece of hardware like an IoT device.
An app is designed to perform some task or help the user perform some task unrelated to the operation of the device itself. This can be anything from media players to word processors, accounting software, social networking software, and everything in between.
