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At Sign

The @ Sign
Icon for the Digital Age

In 1971, Ray Tomlinson, a Principal Scientist at Raytheon BBN Technologies, was already well known for his work on early mail and file transfer programs, but he became better known for a single decision he made while hacking those programs. Tomlinson combined the file transfer protocols of one program with the send and receive message capabilities of two others to create the first electronic email program. The early seventies preceded the advent of the personal computer, so most computers were refrigerator-sized machines that were shared by several people at a site. To address email to an individual user on the computer, Tomlinson needed to indicate both the machine (usually named for the host institution) and the particular user for whom the message was intended, and find a way to separate the two in the address.

An "Obvious" Decision

Ray Tomlinson

Tomlinson looked down at the keyboard he was using, a Model 33 Teletype (which almost everyone else on the early Internet used). He needed a character that would not appear in any host or individual name. In addition to the letters and numerals, the keyboard offered about a dozen punctuation marks. In the second row, on the left side of the keyboard (the keyboard has changed since 1971), Tomlinson spotted the perfect solution. The @ sign didn't appear in names, so there would be no ambiguity about where the separation between login name and host name occurred. The character also had the advantage of meaning "at" the designated institution. It was a brilliant decision that Tomlinson calls "obvious."