"Getting information off the Internet is like taking a drink from a fire hydrant"
Mitchell Kapor, software designer
In 1963, the Advanced Research Project Agency (ARPA) unit, set up by the U.S. Defense Department, began to build a computer network. Driven by fear of the Soviet nuclear threat, it aimed to link computers at different locations, so researchers could share data electronically without having fixed routes between them, making the system less vulnerable to attacks—even nuclear ones.
Data was converted into telephone signals using a modem (modulator-demodulator), developed at AT&T in the late 1950s. In the 1.960s, key advances were made, including "packet switching"—the system of packaging, labeling, and routing data that enables it to be delivered across the network between machines. Paul Baran (b. 1926) proposed this system, which broke each message down into tiny chunks. These would be fired into the network, which would then route ("switch") the various pieces to the desired destination. So, if chunks of a message were traveling from Seattle to New York via Dallas, but Dallas suddenly went offline, the network would automatically route via Denver instead. Different parts—or "packets"—of a message would go by different routes, before being reassembled back into the original message at their destination, even if they arrived in the wrong order. Baran published his concept in 1964, and five years later the new network—called ARPANET—went live.
As the threat of nuclear war receded in the early 1970s, ARPANET was renamed the Internet and effectively opened to all users. Since then, the development of e-mail, the creation of the World Wide Web, and browser technology has enabled the Internet to become a rich communications facility.
