The software component of a computer system that is responsible for managing and coordinating activities and sharing the resources of the computer. The operating system (OS) acts as a host for application programs that are run on the machine. (In computer jargon, application programs are said to run on top of the operating system.) As a host, one of the functions of an operating system is to handle the details of the hardware operation. This relieves application programs from having to manage these details and makes it easier to write applications. Almost all computers use an operating system, such as hand-held computers (including personal data assistants or PDAs), laptop and desktop computers, supercomputers, and even modern video game consoles.