A software program that is developed and used for the purpose of managing the interactions between hardware and software aspects of a computer is called an Operating System (OS). Operating systems manage both the processes of computers as well as the memory. Operating systems also allow computers to communicate between drives, such as the computer's hard drive, floppy drives, jump drives, and CD/DVD Roms. Also, operating systems also control peripheral devices such as keyboards, printers, modems, and scanners. There are several operating systems available today including Microsoft Windows, Mac OS, Linux, MS-DOS, Palm OS, z/OS, and Unix.