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 the @, poised above “P” on his Model 33 teletype. - Continue reading at Smithsonian.com.