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The internet's first message was meant to be "login" — but it crashed at "lo"

45 sec read

In 1969, the first words ever sent between two computers were cut short by a crash, leaving an accidental "lo."

Verified · UCLA (Leonard Kleinrock Center)

At 10:30 p.m. on 29 October 1969, a 21-year-old UCLA graduate student named Charley Kline sat down to connect his computer to a machine 350 miles away at the Stanford Research Institute. The link ran over ARPANET, the research network funded by the US Defense Department that would grow into the internet.

Kline began typing the word “login” so the remote machine would let him in. He got as far as the “l” and the “o” — and then the system crashed.

They succeeded in transmitting the ‘l’ and the ‘o’ and then the system crashed. Hence, the first message on the Internet was ‘lo.’

About an hour later the bug was fixed and the full login went through. Decades on, Kline’s supervisor Leonard Kleinrock liked to point out that “lo” was a happy accident — the opening of “lo and behold.” A more prophetic first word, he argued, could hardly have been chosen.

1969
first message sent
"lo"
what got through
350 mi
UCLA to Stanford

Sources & references

2 references

Well-established. Corroborated by 2 independent sources.

1 UCLA (Leonard Kleinrock Center) academic “They succeeded in transmitting the 'l' and the 'o' and then the system crashed! Hence, the first message on the Internet was 'lo.'” lk.cs.ucla.edu ↗
2 PBS — Evolution Library (WGBH) media “UCLA grad student Charley Kline had been trying to type 'LOGIN,' but the system crashed. About an hour later, he was able to input the full word and connect with a computer at the Stanford Research Institute, 350 miles up the coast.” pbs.org ↗
✓ Last reviewed Jun 6, 2026

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