What was ARPANET and its role in email?
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ARPANET (Advanced Research Projects Agency Network) was the U.S. Department of Defense's experimental network launched in 1969 to connect research computers at universities and government labs. It's the direct ancestor of the internet you're using right now.
Email became ARPANET's killer app almost immediately. By 1973, email accounted for roughly 75% of all ARPANET network traffic. Researchers didn't just use it for work. They built the first online communities, like SF-LOVERS, a mailing list for science fiction fans. (Yes, the first viral email use case was nerds talking about Star Trek.)
ARPANET's architecture set the template for modern email: decentralized nodes, store-and-forward message routing, and open protocols. There was no single company controlling it. Anyone on the network could send to anyone else. That open design is why email still works across every platform today, unlike every closed messaging app that came after.
The protocols developed on ARPANET eventually evolved into SMTP, the standard that powers email delivery in 2025. ARPANET proved that email could scale across institutions, time zones, and organizational boundaries. Without it, email might've stayed trapped inside individual companies' internal systems.
So want to see how those early decisions still matter? Check out how SMTP works, or trace email's evolution from ARPANET to today.
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