ARPA / DARPA is an agency of the Department of Defense in the United States. ARPA was created in 1958, by the then president of the United States: Dwight D. Eisenhower. Eisenhower created ARPA to develop technological systems for the US military. ARPA was renamed to DARPA in the 1970s; it has been renamed back to ARPA since then, but the agency is currently (2014) named DARPA. ARPA and DARPA stand for the following:
ARPA / DARPA has a large remit, and has been involved in creating a wide range of technologies: from ballistic missile defense, to the national aerospace plane, and global positioning systems. ARPA also funded Douglas Engelbart's NLS computer system: which is viewed as being the first modern computer system. In 1968, at the Fall Joint Computer Conference in San Francisco, Engelbart displayed his computer system, which featured: graphics, windows, hypertext, a file directory, a word processor and a computer mouse.
ARPA was created in 1958, and by the early 1960's J. C. R. Licklider became the first director of the 'Information Processing Techniques Office': a department within ARPA. The function of the IPTO was to build information systems for the military. Joseph Licklider proposed the creation of a global computer network in 1963: this network would connect individuals, governments and businesses, and was one of the first memorandums to clearly express a system akin to the Internet.
In 1966, ARPA agreed to fund the creation of a 'wide-area' computer network. It was envisaged that this network would be of military use, and may potentially be capable of surviving a nuclear attack. The idea behind the network: was of a network with no central hub, instead it would be comprised of interconnected autonomous nodes. If one node was destroyed in a military attack, the network and the other nodes would continue to function and communicate. Packet switching was the technology deployed on the network - to transport data between nodes - and in 1969 ARPANET (ARPA computer network) was operational (with four nodes).
ARPA continued to fund the development of ARPANET until 1989: when it was shutdown. The original protocol program of ARPANET - Network Control Program - was 'evolved' by Vint Cerf and Bob Kahn to create TCP/IP. TCP/IP was be applied to ARPANET in 1983. The Internet's core protocols are TCP and IP. Therefore, without the development of ARPANET and the technologies which underpinned ARPANET, the Internet would not exist; and certainly not exist in it's current configuration. The organisations founded to develop ARPANET - Network Working Group and Request for Comments - are still used in the open development process of the Internet (NWG evolved into the IETF).
ARPA / DARPA's involvement in developing ARPANET and the Internet officially ended in 1992; although it had effectively ended in 1973 with the Mansfield Amendment. The Mansfield Amendment dictated that ARPA / DARPA focus primarily on developing technologies with a direct military use. ARPA would focus on developing technologies like the automatic target recognition system, and space propulsion, and not 'basic' science technologies like ARPANET and Douglas Engelbart's NLS computer system. In the early 1990's, the Clinton/Gore administration decided to transition the Internet from being funded and 'controlled' by US governmental agencies - like ARPA / DARPA - to being funded and 'controlled' by commercial networks and nonprofit international organisations (ISOC).