Basic Function of operating system

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.

Why paging is used? -
Paging is solution to external fragmentation problem which is to permit the logical address space of a process to be noncontiguous, thus allowing a process to be allocating physical memory wherever the latter is available.

Functions of an operating system

The basic functions of an operating system are:

Booting the computer
Performs basic computer tasks eg managing the various peripheral devices eg mouse, keyboard
Provides a user interface, e.g. command line, graphical user interface (GUI)
Handles system resources such as computer's memory and sharing of the central processing unit (CPU) time by various applications or peripheral devices
Provides file management which refers to the way that the operating system manipulates, stores, retrieves and saves data.