An operating system (or OS) is a group of computer programs, including device drivers, kernels, and other software that lets people interact with a computer. It manages computer hardware and software resources. It provides common services for computer programs. An OS can be small (like MenuetOS), or large (like Microsoft Windows). Different operating systems can be used for different purposes. Some are used for everyday things like on a personal computer. Others are mobile operating systems or are used for specialized work.