GENERAL DEFINITION OF OS
An OS is a program which acts as an interfacebetween computer system users and the computer hardware.
It provides a user-friendly environment in which a user may easily develop and execute programs.
Otherwise, hardware knowledge would be mandatory for computer programming.
So, it can be said that an OS hides the complexity of hardware from uninterested users
Each program gets space on the resource
May have potentially conflicting goals:
Use hardware efficiently
Give maximum performance to each user