Networks

A computer network consists of two or more computers connected so that they can exchange data and programs. When a computer is a member of a network, the programs it runs and the data it uses can be on the hard disk of some other computer on the network. In business and industrial settings, most computers are on a network. The operating system that runs on a networked computer must manage its share of the network (along with managing all its other responsibilities.) The operating system is able to find programs and data that are stored on other network computers, and copy them into its own main memory.

In a local-area network only a few dozen computers are connected together, usually all located within the same building. Each computer has a network address that the other computers use to access it. Usually the computers share a printer. There may be an especially powerful computer called a server whose hard disk holds all the application programs and data that the other computers are expected to need.

Each computer in a network has a network interface card in its systems unit. This is an input/output device that sends and receives data over cables. The network interface cards of computers on a network are connected together with cables.