An operating system (OS) is the software that manages the sharing of the resources of a computer and provides programmers with an interface used to access those resources. An operating system processes system data and user input, and responds by allocating and managing tasks and internal system resources as a service to users and programs of the system. At the foundation of all system software, an operating system performs basic tasks such as controlling and allocating memory, prioritizing system requests, controlling input and output devices, facilitating computer networking and managing files. Most operating systems come with an application that provides an interface for managing the operating system. The operating system forms a platform for other software. Modern operating systems can be found on anything composed of integrated circuts, like personal computers, internet servers, cellphones, music players, routers, switches, wireless access points, network storage, game consoles, digital cameras, sewing machines and telescopes. Many of the ideas first developed for embedded systems like Forth for telescopes still boot up modern Macintosh computers today, while the PC embedded systems rely on BIOS. The first system put on "bare metal" hardware is usually called firmware. On desktop computers these are the first system you see, such as Amibios or Phoenix bios, for basic input and output of attached components like memory, monitor, and keyboard. Most users equate a visual interface as the "Operating System", such as Desktopenvironment made ubiquitous by the IBM Personal Computer, and recently the Apple _IPod.

Common contemporary desktop OSes are Linux, Mac OS X, Microsoft Windows and Solaris. Windows is most popular on desktops while Linux is most popular in server environments. However, many Linux distributions are gaining in popularity on desktop personal computers, and Sun is attempting to duplicate this achievement with their OpenSolaris OS, which promises to offer the same power, openness, and ease of use that desktop Linux offers. Linux, Mac OS X and MS Windows all have server and personal variants. With the exception of Microsoft Windows, the designs of each of the aforementioned OSs were inspired by, or directly inherited from, the Unix operating system. Unix was developed at Bell Labs beginning in the late 1960s and spawned the development of numerous free and proprietary operating systems.