What the at symbol means
The official name of @ is commercial at. Merchants used it long before computers to mean "at the rate of": 12 apples @ $1 means twelve apples at one dollar each. That is why the sign sat on typewriters and, later, on computer keyboards.
In 1971, programmer Ray Tomlinson chose @ to separate a user name from a computer name when he sent the first email between networked computers, because the sign was on the keyboard and almost never appeared in names. Today it does the same job in every email address ([email protected]) and marks mentions and handles on social media (@username). In casual writing people also use it as short for "at".
Other languages give it playful names. Italians call it chiocciola (snail), Dutch speakers apenstaartje (little monkey tail), Germans Klammeraffe (spider monkey), and Hebrew speakers shtrudel, after the pastry.
How to type @ on any keyboard
On a US keyboard, press Shift + 2 on Windows and Mac. On a UK Windows keyboard, @ moves to Shift + ' (the apostrophe key next to Enter), while UK Mac keyboards keep it on Shift + 2. On German keyboards, use AltGr + Q on Windows and Option + L on a Mac. If nothing else works, Windows users can hold Alt and type 64 on the number pad.
On iPhone and Android, the @ key appears automatically when you type in an email field; otherwise tap 123 (iPhone) or ?123 (Android). In HTML, @ needs no escaping, though HTML5 also has the named entity @.
Fullwidth ＠, small ﹫ and look-alikes
The fullwidth ＠ is the version used in Chinese, Japanese and Korean text, where every character takes the same square width. The small commercial at ﹫ is a compatibility character for small typographic forms. Neither works in a real email address: mail systems expect the plain @, so use the variants only for decoration.
Circled letters such as ⓐ and Ⓐ look a little like @ but are letters, not the at sign. For symbols that go with @ in bios and usernames, see the hashtag symbol and internet symbols pages, or the mail symbol page for envelopes.