From Smithsonian:
The symbol’s modern obscurity ended in 1971, when a computer scientist named Ray Tomlinson was facing a vexing problem: how to connect people who programmed computers with one another. At that time, each programmer was typically connected to a particular mainframe machine via a phone connection and a teletype machine—basically a keyboard with a built-in printer. But these computers weren’t connected to one another, a shortcoming the U.S. government sought to overcome when it hired BBN Technologies, the Cambridge, Massachusetts, company Tomlinson worked for, to help develop a network called Arpanet, forerunner of the Internet. Tomlinson’s challenge was how to address a message created by one person and sent through Arpanet to someone at a different computer. The address needed an individual’s name, he reasoned, as well as the name of the computer, which might service many users. And the symbol separating those two address elements could not already be widely used in programs and operating systems, lest computers be confused.
Tomlinson’s eyes fell on @, poised above “P” on his Model 33 teletype. “I was mostly looking for a symbol that wasn’t used much,” he told Smithsonian. “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 chose @—“probably saving it from going the way of the ‘cent’ sign on computer keyboards,” he says. Using his naming system, he sent himself an e-mail, which traveled from one teletype in his room, through Arpanet, and back to a different teletype in his room. Tomlinson, who still works at BBN, says he doesn’t remember what he wrote in that first e-mail. But that is fitting if, as Marshall McLuhan argued, “The medium is the message.” For with that message, the ancient @, once nearly obsolete, became the symbolic linchpin of a revolution in how humans connect.
More here.
