There were four computers on ARPANET. One each at UCLA, Stanford, UC Santa Barbara, and the University of Utah. At 10:30 PM on October 29, 1969, a message was sent from the computer at UCLA to the one at Stanford. The message was supposed to be the word "login." The "l" and the "o" transmitted without problem but then the system crashed. Hence, the first message on the ARPANET was "lo".