A program is a set of data and code that manipulates it. A process is a program in execution . When a CPU executes a program, the operating system allocates space for data, space for a stack, and space for local variables. Resources Operating System allocates and manages resources needed by processes. For example, if a printer is not managed then get garbled output.
Utilities use the facilities provided by the operating system.
It is a fundamental point that the two goals of an operating system are often contradictory. The operating system should make efficient use of resources . Resources should be used as much as possible and the operating system should finish as many processes as possible. We'll study policies and mechanisms. Whenever possible, the operating system designer should build mechanism, rather than policy.