ARPANET stands for Advanced Research Projects Agency Network. ARPA of the United States Department of Defense developed ARPANET. It is recognized as being the precursor of the Internet. Its design was based on a form of packet switching devised by Larry Roberts, a scientist at the Lincoln Laboratory located in Massachusetts.
J.C.R. Licklider, Beranek, and Newman conceived the idea of the creation of a computer network that could allow communication between users over a network. In 1963, Licklider became the head of the Behavioral Sciences and Command and Control programs at ARPA. During his tenure at ARPA, he managed to convince Ivan Sutherland and Bob Taylor that the creation of a computer network was important. By the middle of 1968, a plan for the development of ARPANET was prepared. After receiving an approval from ARPA, the contract for its development was given to BBN Technologies. BBN was to build a network composed of small computers called Interface Message Processors (IMP). IMPs are now known as routers. In a period of around nine months, a system including a packet switching software and hardware was set up. It was the first functional packet-switching network that was ever built.
The first ARPANET message was sent by Charley Kline, a UCLA student programmer from SDS Sigma 7 Host computer to SDS 940 Host computer in the Stanford Research Institute. It was sent on October 29, 1969. The text in the message was the word 'login'. Only the letters 'l' and 'o' were successfully sent, after which the system crashed.
The TCP/IP was conceived in 1978. DARPA sponsored the development of TCP/IP implementations. The migration from NCP (the protocol used earlier) to TCP/IP took place, and on January 1, 1983, TCP/IP protocols became the only approved protocol on the ARPANET.
In 1990, NSFNET (National Science Foundation Network) started as a backbone to ARPANET. It allowed for the creation of regional and education networks and their connection with university and college campus networks in the United States. In 1995, it was replaced by the backbones offered by Internet service providers.
Today, the Internet has reached far and wide. But it finds its roots in the ARPANET that was built decades ago.