ARPANet = Advanced Research Projects Agency Network.

The precursor to the Internet, ARPANET was a large wide-area network created by the United States Defense Advanced Research Project Agency (ARPA). As an experiment in wide area networking (WAN), ARPANet was developed with the goal of being robust enough to survive a nuclear war. Established in 1969, ARPANET served as a testbed for new networking technologies, linking many universities and research centers.

The ARPANET consisted of individual packet switching computers interconnected by leased lines. Protocols used include FTP and telnet. The first two nodes that formed the ARPANET were UCLA and the Stanford Research Institute, followed shortly thereafter by the University of Utah.

It has now been replaced by NSFnet.