Operating systems is used for managing and controlling various devices such as memory or ram, processor, motherboard, hard disk, power supply, graphic card, keyboard, mouse, monitor, printer and other devices which important for different purposes.

Operating systems is so useful software that helps in our daily work in office, home and other places. We can do many necessary activities in computer by using different operating systems given below:

1. Linux 
2. Microsoft Corporation: Windows 95, Windows 98, Windows Me, Windows NT, Windows 2000, Windows XP (Service Pack 1, 2 and 3), Windows Vista (Service Pack 1 and 2) and Windows 7
3. Apple Computer: Mac OS X, Mac OS X v10.0, Mac OS X v10.1, Mac OS X v10.2, Mac OS X v10.3, Mac OS X v10.4, Mac OS X v10.5 "Leopard" and Mac OS X v10.6 "Snow Leopard"