Ray Tomlinson, who chose the at sign for use in delivering e-mail
Ray Tomlinson, who chose the at sign for use in delivering e-mail

The “at” symbol’s  roots are late medieval. Scribes perhaps created a shortcut ligature of the Latin ad (to or at). The first documented use was in a letter by Francesco Lapi in 1536. The Florentine merchant used @ to denote units of wine called amphorae (large clay jars). Business has long used it to signify “at the rate of,” and it was in such common use by the 19th century that it was included on typewriters as early as 1885. There was no place for @ in traditional typesetting, so there was no nook for the character in the California Job Case.

“@” has long been associated with retail sales and accountancy, but in 1971, Ray Tomlinson (23 April, 1941–5 March, 2016) was working on a way to communicate over a new computer network—the predecessor of the modern-day Internet. “I looked at the keyboard, and I thought: What can I choose here that won’t be confused with a username?” The at sign was an easy choice; it wasn’t commonly used in computing, so there would be no confusion. “It’s the only preposition on the keyboard.”