An operating system provides the environment within that programs are executed. Internally operating systems differ greatly in their makeup because they are organized along many different lines. Design of a new operating system is amajor task. It is essential that goals of the system be well defined before design begins.

We can view an operating system from many vantage points. One view emphases on the services which the system provides, another on the interface which it makes available to users and programmers and a third on its components and their interconnections.