At sign

The at sign (@), otherwise known as the ampersat, is a logogram. It is used in bills, emails and programming. In email, it is used to show a specific domain of an email address. In bills, it used to mean "at a rate of". For example, 7 widgets @ £2 equals £14. In programming, the at sign has been used in a wide range of programming languages. It was invented by Ray Tomlinson.
It is the ligature form of the Latin word "ad", which means "at".
The sign is one of several special symbols on the standard English keyboard.