An operating system (commonly abbreviated OS and O/S) is the software component of a system; it is responsible for the management and coordination of activities and the sharing of the limited resources of the computer. The operating system acts as a host for that are run on the machine. As a host, one of the purposes of an operating system is to handle the details of the operation of the . This relieves application programs from having to manage these details and makes it easier to write applications. Almost all computers, including , , and even , use an operating system of some type. Some of the oldest models may however use an embedded, that may be contained on a compact disk

Operating systems offer a number of services to application programs and users. Applications access these services through application programming interfaces (APIs) . By invoking these interfaces, the application can request a service from the operating system, pass parameters, and receive the results of the operation. Users may also interact with the operating system with some kind of software user interface (UI) like typing commands by using (CLI) or using a (GUI, commonly pronounced Googey). For hand-held and desktop computers, the user interface is generally considered part of the operating system. On large multi-user systems like Unix and Unix-like systems, the user interface is generally implemented as an application program that runs outside the operating system. (Whether the user interface should be included as part of the operating system is a point of contention.)

Common contemporary operating systems include solaris. Microsoft Windows has a significant majority of market share in the desktop and notebook computer markets, while servers generally run on Linux or other Unix-like systems. Embedded device markets are split amongst several operating systems