An operating system is a system software that acts as an interface between the user and hardware resources. It controls and co-ordinates the hardware used by various application programs. OS acts as resource allocator and manager. Since, there are many possible conflicting requests for resources, the OS must decide which requests are allocated resources to operate the computer system efficiently and fairly. An OS is a control program, which controls the user programs to prevent errors and improper use by the computer. It is especially concerned with the operation and control of I/O devices. Main functions of an OS are as follows:
1. Processor management
2. Memory management
3. File management
4. Device management
5. Storage management
