OS

An operating system (OS) is software that manages computer hardware and software resources and provides common services for computer programs. The operating system is an essential component of the software in a computer system. Application programs usually require an operating system to function.

Operating systems can be found on many devices that contain a computer—from cellular phones and video game consoles to supercomputers and web servers. Examples of popular modern operating systems include Android, BSD, iOS, Linux, OS X, QNX, Microsoft Windows, Windows Phone, and IBM z/OS. All these examples, except Windows, Windows Phone and z/OS, share roots in UNIX.