Operating System: - An operating system is a system software which is used to operate a computer its work as an interface between user and machine it’s may enabled to computer hardware. In other word we can say that “ An operating system is a program that acts as an interface between the user and the computer hardware and controls the execution of all kinds of programs . ” An O perating System or OS is a software program that enables the computer hardware to communicate and operate with the computer software . Without a computer operating system, a computer and software programs would be useless Some popular Operating Systems include UNIX Linux, Windows,ANDROIDetc. Types of Operarting system:- Single user Single Tasking Single user Multitasking Multiuser Multitasking