text: *History*\nThe @ sign may have evolved from the Norman French "à"\n\n@ appears to be the cursive form of ā, an abbreviation of an unknown word beginning with a. In medieval European manuscripts, abbreviations were generally indicated by drawing a line over or through the letters, as in the common IX for Jesus Christ, or # from lb for libra 'pound'. In the typeface of the Gutenberg Bible, ā stands for either an or am within words. However, it is not known which particular word gave rise to modern @.\n\nA commonly accepted theory is that the symbol is derived from the Latin preposition ad, which means about with numerals. However, no document showing this usage has been presented.\n\nA similar idea is that @ is the abbreviation of the Greek preposition ana (ανά), which means 'at the rate of' when used with numerals, exactly its modern commercial usage.\n\nA more recent idea has been proposed by Giorgio Stabile, a professor of history in Rome. He claims to have traced the symbol back to the Italian Renaissance in a Venetian mercantile document signed by Francesco Lapi on May 4, 1536. The document talks about commerces with Pizarro and in particular the price of an @ of wine in Peru, where <@> stood for amphora (Italian anfora; Spanish and Portuguese arroba). The word arroba still means both the @ symbol and a unit of weight (see below). Under this view, the symbol was used to represent one amphora, which was a unit of weight or volume based upon the capacity of the standard terracotta jar, and came into use with the modern meaning "at the rate of" in northern Europe.\n\nHowever, @ could be the abbreviation of any word beginning in a, and more than one such symbol was likely in use, but there is no continuous record between any of the possibilities and the modern symbol.\n\nAn alternative view is that it derives from Norman French "à" meaning "at" in the sense of "each". "2 widgets à £5.50 = £11.00" is the sort of accountancy shorthand notation you will see on English commercial vouchers and ledgers all the way into the 1990s, where the usage was superseded for accountants with its e-mail usage. It is used in this way in Modern French also.\n\nAccording to this view, the @ symbol is simply a stylish way of writing the à, so as not to remove the hand from the page in making the symbol. You can see hybrids between @ and à in French handwriting in street markets to this day.\n\n*Modern uses*\nThe symbol's most familiar modern use is in e-mail addresses (sent by SMTP), as in jdoe@example.com ("the user named ‘jdoe’ working at the computer named ‘example’ in the ‘com’ domain"). Ray Tomlinson is credited with the introduction of this use in 1972. This idea of user@host is seen in many other tools and protocols as well: for example, the command ssh jdoe@www.example.com would try to establish a ssh connection to the box with the hostname www.example.com using the username jdoe.\n\nIn the programming language Perl, the symbol prefixes variables which contain arrays, as opposed to scalar values (indicated with '$') and hash tables / associative arrays ('%'). If the code were to be treated as a sentence, this prefix would be the equivalent of a determiner, so "@animals" might be read as "these animals".\n\nIn the IRC protocol, @ is the symbol for a channel operator. IRC also uses the user@host form (often preceded by nick!) for identifying and banning users. In this case the user@ part was originally an ident response and the host part was a reverse dns name from the user's IP. However, most modern IRC networks provide some mechanism for users to hide their real reverse dns hostname and/or for admins/privileged users to pick one arbitrarily.\n\nThe @ character is also used as an alternative political spelling for typing in some Romance languages as a gender-neutral substitute for the 