A desktop computer is a personal computer that is designed to fit conveniently on top of a typical office desk. A desktop computer typically comes in several units that are connected together during installation: (1) the processor, which can be in a microtower or minitower designed to fit under the desk or in a unit that goes on top of the desk, (2) the display monitor, (3) and input devices - usually a keyboard and a mouse. Today, almost all desktop computers include a built-in modem, a CD-ROM drive, a multi-gigabyte magnetic storage drive, and sometimes a diskette drive. At home, most desktop computer users also purchase a printer. In businesses and increasingly at home, desktop computers can be interconnected and can share resources such as printers by being connected to a local area network (LAN).