The world's largest network of computer networks got its original name from the U.S. military arm that funded it: Arpanet was for the Advanced Research Projects Agency. Back in 1969 when Arpanet was created, it connected five sites: UCLA, Stanford, UC Santa Barbara, the University of Utah and BBN. In 1983, the U.S. Defense Department spun-off MILNET*, which was the part of Arpanet that carried unclassified military communications. Arpanet was renamed the Internet in 1984, when it linked 1,000 hosts at university and corporate labs.
*MILNET was later re-named the Defense Data Network and finally NIPRNET, for Non-classified IP Router Network.