The operating system is a collection of software components of a computer system which is reliable for the management, coordination and the sharing of the resource of the computer. It is employ to manage the computer hardware and also provide interface for the users. It also gives isolation, security and protection among numbers of user programs. The operating system is acts as mediator between the user and hardware of the computer. There are some example of desktop operating system are Unix, Microsoft windows xp, windows 7, windows 8.1, Linux, os2 etc. It has greater responsibilities and power for a large system. Every general purpose computer must have an operating system to execute other programs and applications. The operating system is capable for supporting and utilizing more than one computer. It can handle input and output to and from attached hardware devices, such as printers, hard disks and dial up ports.