The longhairs with the pocket protectors had already set up the lines between USC and Stanford and UC Santa Barbara. It was 1969, a weird year of technological and social progress (Apollo 11, Mariner 6 and 7, the Stonewall Riots) and de-evolution (President Richard Nixon, the Manson Murders). Students were still seizing campus buildings—SDS took the Harvard administration building that spring—but on this day 43 years ago, the hippie nerds in the computer labs made the last connection in their four-node Defense Department-funded networked computer project. The fourth computer came online at the University of Utah.
The first text transmission using the new packet-switching technology was "lo," from UCLA to Stanford. The programmer had intended to type "login," but the computer crashed before the third character of text was sent.
Eventually these early "tech support" guys got everything rebooted and sent the entire word. Once the nation's best university computer departments were connected and the ARPANET was deemed functional in 1975, the Pentagon said "thank you" and seized control of the entire project. There is a persistent version of history that claims packet-switching networks were specifically developed so that a decentralized ARPANET could survive a nuclear war, but Internet historians say it was developed because everything was so unreliable on a good day that the ability to reassemble chunks of data in their intended order was essential for any binary network. (Paul Baran of the RAND Corporation suggested a distributed network to survive a nuclear war, because that's the kind of thing they plan on, at the RAND Corporation.)
Not until 1981 did the Defense Department split the classified between MILNET and the National Science Foundation's more open network, CSNET. A year later, a universal protocol called TCP/IP appeared, and by 1986 the increasingly powerful network of supercomputers was expanded to the NSFSNET, which means "not safe for work." The public quickly filled the the new Internet with ASCII pornographic images until the World Wide Web arrived in the early 1990s to facilitate the global distribution of .gifs and alt.startrek.erotica and Cyber Monday deals in household appliances. Happy birthday, ARPANET!