A mobile application (also called a mobile app) is a type of application designed to run on a mobile device, which can be a smartphone or tablet computer. Even if apps are usually small software units with limited function, they still manage to provide users with quality services and experiences. Contrary to applications designed for desktop computers, mobile applications move away from integrated software systems. Instead, each mobile app provides an isolated and limited functionality. For example, it can be a game, a calculator, or a mobile web browser. Because of the limited hardware resources of the early mobile devices, mobile apps avoided multi-functionality. However, even if the devices used today are far more sophisticated, mobile apps remain narrowly functional. This is how mobile app owners allow consumers to handpick exactly the functions their devices should have.