Wide-Area Networks

Large organizations need to connect many more computers than can be handled with a local area network. A wide-area network can connect thousands of computers together over great distances. The long distance connections are made by using optical fiber, telephone lines, microwave radio, and satellite communications. Each computer in the network has a network address (as with local-area networks) to uniquely identify it.

Wide-area networks use a variety of special hardware to manage the flow of data. When two computers share data, this hardware makes it appear that the two computers are connected together directly. In reality, there may be dozens of network devices between the two computers.

All these devices use the same method for dealing with data. Without a common method of dealing with data, a large network would become a hopeless muddle. An agreement about how to represent and transmit data over a network is called a protocol. Usually large networks use a protocol called TCP/IP (for transmission control protocol / internet protocol).