What are the basic functions of an operating system?

Operating system controls and coordinates the use of the hardware among the various applications programs for various uses. Operating system acts as resource allocator and manager.

Since there are many possibly conflicting requests for resources the operating system must decide which requests are allocated resources to operating the computer system efficiently and fairly.

Also operating system is control program which controls the user programs to prevent errors and improper use of the computer.

It is especially concerned with the operation and control of I/O devices.