Networks are connections between groups of computers and associated devices that allow users to transfer information electronically. The local area network shown on the left is representative of the setup used in many offices and companies. Individual computers are called work stations (W.S.), and communicate to each other via cable or telephone line linking to servers. Servers are computers exactly like the W.S., except that they have administrative functions and are devoted entirely to monitoring and controlling W.S. access to part or all of the network and to any shared resources (such as printers). The red line represents the larger network connection between servers, called the backbone; the blue line shows local connections. A modem (modulator/demodulator) allows computers to transfer information across standard telephone lines. Modems convert digital signals into analog signals and back again, making it possible for computers to communicate, or network, across thousands of miles.
