According to a blogger with the New York Times, the @ sign used in every email address on the planet is older than you might think, “@ least 473 years old.” Robert Mackey references Tony Long of Wired Magazine who points out that the sign has Italian origins (they call it a “snail” instead of “at sign”) and was used originally as an abbreviation for a unit of measure called the amphora. An amphora equals about 25 pounds of a solid or 3 gallons of liquid.
How did it get to be the centerpiece of every email address? First, it had to make it to the standard typewriter keyboard as an accounting shorthand symbol (in English) for “at the price of.” In 1971, computer geek patriarch Ray Tomlinson decided to use it when sending “the first network email” to indicate that the user was “at” some other host rather than being on a local server. Carets (^), ampersands (&), and tildes (~) have been jealous ever since!