On 29 October 1969, computer science student Charley Kline at UCLA transmitted the first message over ARPANET — the precursor to the internet — to a computer at the Stanford Research Institute 350 miles away. The intended message was "login." The system crashed after the first two letters, making **"lo"** the first transmission ever sent over a computer network.
ARPANET was funded by the US Defense Advanced Research Projects Agency (DARPA) and designed to be a resilient packet-switching network that could route traffic around damage, including nuclear strikes. By 1971 it connected 23 sites; by the early 1980s it had become the backbone of a global academic network and given birth to email and file-sharing.
In 1983, ARPANET adopted the TCP/IP protocol that still underlies the internet. In 1990 it was decommissioned as the public internet took over. The internet now connects over 5 billion people and carries the bulk of global communication, commerce, and knowledge.