atsigns

Atsigns, represented by the symbol @, are a widely recognized typographical character used in a variety of contexts. Originating in the early medieval period, the sign was first employed as a shorthand for the Latin word "ad," meaning “at” or “to.” It entered commercial use in the 16th and 17th centuries as a symbol for “at the rate of,” appearing on shop signs and ledgers. The symbol’s inclusion in early computer systems emerged with the development of the first email protocols; in 1971, Ray Tomlinson chose @ to separate the user name from the host name in electronic mail addresses, establishing a convention that persists in modern email addresses worldwide.

In contemporary digital communication, atsigns function as handles or nicknames, most notably on the microblogging platform Twitter and the messaging application Slack. A user's handle begins with @ to allow the system to resolve identifiers efficiently and to facilitate mentions or direct messages. In many operating systems, the @ symbol is also employed in shell scripting and programming languages to denote annotations, decorators, or to reference symbolic links.

Unicode assigned the atsign a unique codepoint (U+0040) in the ASCII block, ensuring consistency across platforms. The character is encoded as a printable, non-alphanumeric symbol, and its rendering is supported by all major fonts. Despite its ubiquity, the exact shape of the atsign varies across typefaces; some stylize it with a tail or adjust its counter to accommodate design aesthetics. The symbol’s functional versatility and historical depth have made it an enduring element of digital and commercial notation.