Operating Systems

An operating system (OS) is a software that manages computer resources 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. 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. Operating systems can be found on almost anything made with integrated circuits, such as personal computers, internet servers, cellphones, music players, routers, switches, wireless access points, network storage, game consoles, digital cameras, sewing machines and telescopes.

In most cases, the operating system is not the first code to run on the computer at startup (boot) time. The initial code executing on the computer is usually loaded from firmware, which is stored in Flash ROM. This is sometimes called the BIOS or boot ROM. The firmware loads and executes the operating system kernel (usually from disk, sometimes over the network), and is usually responsible for the first graphics or text output the user sees onscreen.

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. 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.

Many users equate the desktop environment with the underlying operating system