On what date was the first ARPANET message sent?

The first ARPANET message was sent on October 29, 1969. The successful connection ran between UCLA and the Stanford Research Institute (SRI), marking the first host-to-host communication on the network that preceded today’s Internet.

UCLA student programmer Charley Kline attempted to log in to SRI’s computer, where Bill Duvall was monitoring the receiving system. Kline typed “login,” but the remote computer crashed after receiving only the first two letters. After the system was adjusted, the second attempt succeeded, making “lo” the first two characters transmitted. The full login was completed shortly afterward.

The date can occasionally cause confusion because the event occurred at 10:30 p.m. Pacific time on October 29, which was October 30 in UTC. The later addition of nodes at UC Santa Barbara and the University of Utah expanded ARPANET into its original four-node network by December 5, 1969. This was not the first email or a public Internet message; it was a host-to-host login over an experimental packet-switching network.