via shady characters
“Like the ampersand, the ‘@’ symbol is not strictly a mark of punctuation; rather, it is a logogram or grammalogue, a shorthand for the word ‘at’. Even so, it is as much a staple of modern communication as the semicolon or exclamation mark, punctuating email addresses and announcing Twitter usernames. Unlike the ampersand, though, whose journey to the top took two millennia of steady perseverance, the at symbol’s current fame is quite accidental. It can, in fact, be traced to the single stroke of a key made almost exactly four decades ago…”
Read the rest here, and a bit more here. Part 2 of the series can be found here.