App

An app, short for "application," is a type of software designed to perform a specific function or set of functions on a computer or mobile device. Apps can range from simple utilities like calculators or weather apps, to more complex programs like photo editors or video games.
Apps can be downloaded and installed onto a device from an app store or marketplace, or they can be accessed through a web browser. They may require an internet connection or function offline, and they can be free or paid.
Apps can be developed for a variety of operating systems, such as iOS, Android, Windows, or macOS, and they can be programmed using a variety of programming languages and frameworks.