SRI, then called the Stanford Research Institute, demonstrated the first ARPANET host-to-host connection with UCLA. On October 29, 1969, UCLA computer scientist Leonard Kleinrock’s team attempted to send the word “LOGIN” to SRI, the network’s second node.
The first transmission failed after the system received only “LO” and the SRI host crashed. The researchers restarted the machines and completed the connection during a second attempt. This event is widely treated as the first successful host-to-host communication over ARPANET, the packet-switched research network funded by the U.S. Advanced Research Projects Agency.
SRI was not Stanford University itself, although the names are related and the institute originated at Stanford. SRI operated the Network Information Center and hosted the second ARPANET node, while UCLA hosted the first. Another common mix-up is confusing this milestone with the later invention of the World Wide Web or with the first email; those developments came afterward and represent different milestones.