In 1971, Tomlinson was developing a messaging system for an early ancestor of the modern Internet called ARPAnet. There was one problem that gave him particular trouble, he told Smithsonian in 2012: how to separate out the name of the message recipient from the name of their computer. He needed some sort of symbol, but it couldn’t be a popular one, or one that computers might know in a different context. It also needed to be present on keyboards at the time. @ was there, and pretty much no one used it. It was perfect.
“I was mostly looking for a symbol that wasn’t used much,” he said in the Smithsonian interview, “And there weren’t a lot of options — an exclamation point or a comma. I could have used an equal sign, but that wouldn’t have made much sense.”
Tomlinson was among the first class of people inducted into the Internet Hall of Fame in 2012, by which time the @ symbol had lept beyond the familiar email usage and into social media (see: Twitter) and colloquial conversation.
“It has truly become a way of expressing society’s changing technological and social relationships, expressing new forms of behavior and interaction in a new world,” The Museum of Modern Art wrote in 2010, when it announced that it had acquired the symbol for its Architecture and Design collection.
MoMA’s research indicates that the symbol could date back as far as the 7th century, as a way of writing the Latin word “ad” in one swipe. “Ad” translates to “at” or “toward,” which means that if this is actually the symbol’s origins, then it has always carried a similar meaning to its current, popular use. Another similar theory, as Wired noted, is that the symbol was a shorthand for “à” in Italian, which can also mean “at.”
Why would one need this shorthand? Well, the theory goes, it could have been the innovation of some early monk, looking for shortcuts while transcribing the Holy Scriptures by hand.
In any case, the earliest recorded usage of the @ symbol comes from Venetian traders in the 16th century, who used it to refer to an amphora, or a jar that could carry grains or liquids and was considered a unit of measurement. A 1536 letter from the merchant Francesco Lapi contained the sentence, “There, an amphora of wine, which is one thirtieth of a barrel, is worth 70 or 80 ducats,” where “amphora” was written as “@,” an Italian scholar explained to the Guardian in 2000.
The mark, retaining almost exclusively an accounting or transactional meaning, was standard on typewriter keyboards in reference to this usage and was still present on the Model KSR 33 Teletype that Tomlinson was using when he gave the symbol a new lease on life.
In case you were curious: Tomlinson sent the first email to use the now ubiquitous user@host address to himself. What it actually said, though, is lost to time: In many interviews over the years, Tomlinson has said that he doesn’t remember what he wrote.