The at sign was used in commerce long before it became a standard part of email addresses.

The longer version

Merchants needed a compact way to write unit prices, so the symbol stood for at the rate of: seven pounds of sugar at a fixed price per pound. Invoices, ledgers and price lists used it for centuries because it saved space in a narrow column and could not be misread as a number.

Keyboard makers kept it partly for that commercial habit, which is why it survived into the computer age. When early email engineers needed a way to separate a user name from a host machine, they chose the one punctuation key on the standard keyboard that had no other role in addresses or commands.

Where this entry sits

This category gathers small surprises about the English language, from odd spelling rules to words that quietly hide their own history. Expect palindromes, punctuation oddities, borrowed terms, and the strange ways writing systems record spoken speech. The full list sits on the Words and Language page, where every entry is listed in order.