Operating system is a collection of system. Programs that together control the operation of a computer system.
The operating system along with hardware application and other system softwares and users constitute a computer system.
It is most important part of any computer system.
It acts as an intermediatry between a user and the computer hardware. The operating system has two objectives.
Firstly an operating system controls the computer hardware. The second objective is to provide an interactive interface to the user and interpret commands so that it can communication with the hardware.