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 fiber optic lines, telephone lines, microwave communications, 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.)

The Internet consists of many wide-area networks that have been connected together to form one huge worldwide network. Even on this huge network, each computer must have a unique network address, much like each telephone in the world has a unique telephone number (if you include the country code and area code.)