A correspondent writes to ask what is the 'official' name for the @ sign, if there is one.
Well, I guess it all depends on what one means by 'official'. What is official in one context may not be so in another - and that is the case with this sign. Traditionally, it was officially referred to as 'commercial at', because of its origins in commercial accounting; and that is the way it's described in the Unicode system and in the Telecoms standardization system (what used to be called CCITT). On the other hand, the majority usage today is in computing contexts, so that term seems a bit antiquated.
Modern terms whch have been proposed include 'asperand' and 'ampersat', but neither has more than a few thousand hits on Google. 'Amphora' is another suggestion, derived from the medieval symbol used as a measure of quantity (an amphora was a kind of jar).
Personally, I think the best technical term in English for the at sign is 'at sign'.
Note that other languages have opted for different solutions, usually based on the shape of the symbol, such as Dutch apenstaartje ('little monkey-tail'), Hungarian kukac ('worm, maggot'), and so on. There are several lists available on the Web (if you type in 'at sign' into a search engine).