On October 4, 1957, the Soviets launched Sputnik, man's first foray into outer space, and the U.S. government under President Eisenhower subsequently launched an aggressive military campaign to compete with and surpass the Soviet activities. From the launch of Sputnik and the U.S.S.R. testing its first intercontinental ballistic missile, the Advanced Research Projects Agency (ARPA) was born. ARPA was the U.S. government's research agency for all space and strategic missile research. In 1958, NASA was formed, and the activities of ARPA moved away from aeronautics and focused mainly on computer science and information processing.
One of ARPA's goals was to connect mainframe computers at different universities around the country so that they would be able to communicate using a common language and a common protocol. Thus the ARPAnet -- the world's first multiple-site computer network -- was created in 1969.
The original ARPAnet eventually grew into the Internet. The Internet was based on the concept that there would be multiple independent networks that began with the ARPAnet as the pioneering packet-switching network but would soon include packet satellite networks and ground-based packet radio networks.
Computers were added quickly to the ARPANET during the following years, and work proceeded on completing a functionally complete Host-to-Host protocol and other network software. In December 1970 the Network Working Group (NWG) working under S. Crocker finished the initial ARPANET Host-to-Host protocol, called the Network Control Protocol (NCP). As the ARPANET sites completed implementing NCP during the period 1971-1972, the network users finally could begin to develop applications.
In October 1972 Kahn organized a large, very successful demonstration of the ARPANET at the International Computer Communication Conference (ICCC). This was the first public demonstration of this new network technology to the public. It was also in 1972 that the initial "hot" application, electronic mail, was introduced. In March Ray Tomlinson at BBN wrote the basic email message send and read software, motivated by the need of the ARPANET developers for an easy coordination mechanism. In July, Roberts expanded its utility by writing the first email utility program to list, selectively read, file, forward, and respond to messages. From there email took off as the largest network application for over a decade. This was a harbinger of the kind of activity we see on the World Wide Web today, namely, the enormous growth of all kinds of "people-to-people" traffic.
timeline of the Internet. google