ARPAnet: The World's First Internet

ARPA network map in 1973. Public Domain

On a cold war kind of day in 1969, work began on ARPAnet, the grandfather to the Internet. Designed as a computer version of the nuclear bomb shelter, ARPAnet protected the flow of information between military installations by creating a network of geographically separated computers that could exchange information via a newly developed technology called NCP or Network Control Protocol.

ARPA stands for the Advanced Research Projects Agency, a branch of the military that developed top secret systems and weapons during the Cold War. But Charles M. Herzfeld, the former director of ARPA, stated that ARPAnet was not created due to military needs and that it “came out of our frustration that there were only a limited number of large, powerful research computers in the country and that many research investigators who should have access were geographically separated from them." 

Originally, there were only four computers connected when ARPAnet was created. They were located in the respective computer research labs of UCLA (Honeywell DDP 516 computer), Stanford Research Institute (SDS-940 computer), University of California, Santa Barbara (IBM 360/75) and the University of Utah (DEC PDP-10). The first data exchange over this new network occurred between computers at UCLA and the Stanford Research Institute. On their first attempt to log into Stanford's computer by typing "log win," UCLA researchers crashed their computer when they typed the letter 'g.'

As the network expanded, different models of computers were connected, which created compatibility problems. The solution rested in a better set of protocols called TCP/IP (Transmission Control Protocol/Internet Protocol) that were designed in 1982. The protocol worked by breaking data into IP (Internet Protocol) packets, like individually addressed digital envelopes. TCP (Transmission Control Protocol) then makes sure the packets are delivered from client to server and reassembled in the right order.

Under ARPAnet, several major innovations occurred. Some examples are email (or electronic mail), a system that allows for simple messages to be sent to another person across the network (1971), telnet, a remote connection service for controlling a computer (1972) and file transfer protocol (FTP), which allows information to be sent from one computer to another in bulk (1973). And as non-military uses for the network increased, more and more people had access and it was no longer safe for military purposes. As a result, MILnet, a military only network, was started in 1983.

Internet Protocol software was soon being placed on every type of computer. Universities and research groups also began using in-house networks known as Local Area Networks or LANs. These in-house networks then started using Internet Protocol software so one LAN could connect with other LANs.

In 1986, one LAN branched out to form a new competing network called NSFnet (National Science Foundation Network). NSFnet first linked together the five national supercomputer centers, then every major university. Over time, it started to replace the slower ARPAnet, which was finally shutdown in 1990. NSFnet formed the backbone of what we call the Internet today.

Here’s a quote from the U.S. Department report The Emerging Digital Economy:

"The Internet's pace of adoption eclipses all other technologies that preceded it. Radio was in existence 38 years before 50 million people tuned in; TV took 13 years to reach that benchmark. Sixteen years after the first PC kit came out, 50 million people were using one. Once it was opened to the general public, the Internet crossed that line in four years."  

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Your Citation
Bellis, Mary. "ARPAnet: The World's First Internet." ThoughtCo, Aug. 27, 2020, Bellis, Mary. (2020, August 27). ARPAnet: The World's First Internet. Retrieved from Bellis, Mary. "ARPAnet: The World's First Internet." ThoughtCo. (accessed March 27, 2023).