Sponsored by the U.S. Department of Defense Advanced
Research Projects Agency, ARPANET was a wide area network (see WAN)
that linked computers at
research centers around the United States. It was the first computer network and the forerunner of today''s Internet. In the 1960s, the Defense Department was interested in creating a nonhierarchical, geographically dispersed communications system that would allow the military to
communicate even if one or more key links were destroyed during a nuclear war. At that time, no standard computer operating system existed; thus, computers generally could not communicate with one another. Academic computer scientists were hired to develop the network, which was launched in 1969 with four nodes, or sites: the University of California at Los Angeles; the University of California, Santa Barbara; Stanford Research Institute; and the University of Utah. By 1971, ARPANET had expanded to 23 sites; by 1981, to over 200. Although the original purpose of ARPANET was restricted to Defense Department projects, it quickly became a way for academics to communicate on a myriad of nondefense topics. Scientists without Defense Department clearance were denied access to ARPANET, so in 1979 an academic network, Usenet News, began; its nodes eventually connected with those of ARPANET.