ARPANET and personal computers. ARPANET was developed in 1968 by the Advanced Research Projects Agency of the U.S. Department of Defense and implemented in 1969 by Bolt, Beranek, and Newman both as a network research project per se and, as it turned out, a very successful method to link military research computers. It demonstrated the viability and system-wide reliability of long-haul packet-switched networks. The development of the Transmission Control Protocol (TCP) and the Internet Protocol (IP) in the mid to late 1970s enabled the linking of a growing number of wide area and local area networks via ARPANET and thus greatly increased the number of researchers with network access. This linking of a number of networks eventually led to the use of the name "ARPA Internet" in 1977 to stress the internetwork aspects of this growing resource for scientific research. More formally, "Internet" was formed in 1983, when the Defense Communications Agency reorganized military networking and mandated the use of the TCP/IP protocols for all hosts on military networks.
In the mid to late 1980s the National Science Foundation (NSF) established a number of supercomputer centers to make greatly increased computing power available to the broad spectrum of research scientists outside of the military research community. After some initial experience using ARPANET, NSF established the NSFNET backbone for the Internet in 1987 and 1988 and began to link an increasing number of colleges and universities to the network. This greatly increased both the capacity and number of users on the network and reinforced the fact that the original ARPANET had become only one of the many networks on an already large and continually growing Internet.