An operating systems (OS) are a collection of software that manages computer hardware resources and provides common services for computer programs. The operating systems are an essential component of the system software in a computer system. Application program usually require an operating system to function.
Time-sharing operating system schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor times, mass storages, printings, and other resources.
For hardware function such as input and output and memory allocation, the operating system acts as an intermediary between program and the computer hardware, although the applications codes are usually executed directly by the hardware and will frequently make a system call to an OS function or be interrupted by it. Operating systems can be founds on almost any devices that contain computer—from cellular phones and video game consoles to supercomputers and web servers.
Examples of popular modern operating systems include Androids, BSDs, iOSs, Linuxs, OS X,QNX, Microsoft Windows, Windows Phones, and IBM z/OS. All these, except Windows, Windows Phone and z/OS, share root in UNIX.