sourced story
October 29, 1969General sourceWell documented

ARPANET sends its first message

On the timeline · around October 29, 1969 · ARPANET sends its first message1964196619681970197219741976

What happened

UCLA student Charley Kline tried to send "LOGIN" to Stanford; the network crashed after "LO" — the first message on the ARPANET, the internet's direct ancestor.

Why it matters

Two computers talking over a packet-switched network: the internet's opening syllable.

Sources

ARPANET sends its first message — A Timeline of the Internet & Computing · SourcedStory