Internet

                                         Internet (1969)

Advanced Research Project Agency (ARPA) develops the first computer network.

       In 1963, the advanced research project agency (ARPA) unit,set up by the U.S. Defence Department, Began to build a computer network.driven by fear of sovient 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 (modulated-demodulator),developed at AT&T in the late 1950s.in the 1960s,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 then route ("Switch") the various pieces to desired destination. So, if chunks of message were travelling from seattle to New york via Dallas, but Dallas suddenly went offline, the network would go by 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 wrong order.baran publised his concept in 1964, and five years later the new network --called ARPANET--went live.