The ARPANET and the DARPA Internet

The ARPANET, initiated in 1969 by the Advanced Research Projects Agency (DARPA) of the Department of Defense (DoD), was the first wide area packet switching network. In 1984, the ARPANET, which had grown to over 100 nodes, was separated into two parts: an operational component, the MILNET, to serve the operational needs of the DoD, and a research component that retained the ARPANET name. After the network split, the MILNET expanded, and it should reach over 250 nodes within a year. The DARPA Internet was formed in the 1970s in response to a requirement to interconnect different types of packet‐switching networks that were being implemented. It has grown to be very large; it now consists of over 330 networks, hundreds of gateways, and tens of thousands of hosts. Where the ARPANET used to connect hosts that were single computers into a network, many of these hosts now serve as gateways to local campus networks, regional networks, and other national networks, such as the NSFNET. The impact of this growing system of inter‐connected networks on research, communications, and library access will be profound.