The at sign, @, normally read aloud as "at", also commonly called the at symbol or commercial at, and less commonly a wide range of other terms, is originally an accounting and commercial invoice abbreviation meaning "at the rate of" (e.g. 7 widgets @ £2 = £14). In recent years, its meaning has grown to include the sense of being "located at" or "directed at", especially in email addresses and social media, particularly Twitter.
It was not included on the keyboard of the earliest commercially successful typewriters, but was on at least one 1889 model and the very successful Underwood models from the "Underwood No. 5" in 1900 onward. It is now universally included on computer keyboards. The mark is encoded at U+0040@commercial at (HTML: @).
The fact that there is no single word in English for the symbol has prompted some writers to use the French arobase or Spanish and Portuguese arroba—or to coin new words such as asperand,ampersat or apetail—but none of these has achieved wide usage.
@ symbol used as the initial "a" for the "amin" (amen) formula in the Bulgarian translation of the Manasses Chronicle (c. 1345).
There are several theories about the origin of the commercial at character.
One theory is that the symbol developed as a mercantile shorthand symbol of "each at"—the symbol resembling a small "a" inside a small "e"—to distinguish it from the different "at" (symbolized by the mere letter "a") or "per." For example, the cost of "12 apples @ $1" would be $12, whereas the cost of "12 apples at $1" would be $1—a crucial and necessary distinction.
Another theory is that medieval monks abbreviated the Latin word ad (at, toward, by, about) next to a numeral. One reason for this abbreviation was that it saved space and ink. Since thousands of pages of biblical manuscripts were copied onto expensive papyrus or hides, and the words at, toward, by and about repeated millions of times throughout the ages, a considerable amount of resources could be spared this way. A theory concerning this graphic puts forward the idea that the form derives from the Latin word ad,[clarification needed] where the d is spelled in capital, and then inversed back over the a in front of it, thus forming a shape that resembles the @.
It has been theorized that it was originally an abbreviation of the Greek preposition ανά (transliterated ana), meaning at the rate of or per.
Another theory is that it derives from the Norman French "à" meaning "at" in the "each" sense, i.e. "2 widgets à £5.50 = £11.00", comes the accountancy shorthand notation in English commercial vouchers and ledgers to the 1990s, when the email usage superseded the accountancy usage. It is also used like this in Modern French, Swedish or Czech; in this view, the at-symbol is a stylised form of à that avoids raising the writing hand from the page in drawing the symbol; this compromise between @ and à in French handwriting is found in street market signs.
Whatever the origin of the @ symbol, the history of its usage is more well-known: it has long been used in Spanish and Portuguese as an abbreviation of arroba, a unit of weight equivalent to 25 pounds, and derived from the Arabic expression of "a quarter" (الربع pronounced ar-rubʿ). An Italian academic claims to have traced the @ symbol to the 16th century, in a mercantile document sent by Francesco Lapi from Seville to Rome on May 4, 1536. The document is about commerce with Pizarro, in particular the price of an @ of wine in Peru. In Italian, the symbol was interpreted to mean amphora (anfora). Currently, the word arroba means both the at-symbol and a unit of weight. In Italian, the symbol represents one amphora, a unit of weight and volume based upon the capacity of the standard amphora jar, and entered modern meaning and use as "at the rate of" or "at price of" in northern Europe.
Until now, the first historical document containing the @ symbol as a commercial one is the Spanish "Taula de Ariza", a registry to denote a wheat shipment from Castile to Aragon in the year 1448.
In contemporary English usage, @ is a commercial symbol, called at site or at rate meaning at and at the rate of. It has rarely been used in financial documents[clarification needed] or grocers' price tags, and is not used in standard typography.
Since 23 October 2012, the At-sign is registered as a trade mark by the German Patent and Trade Mark Office – DPMA (registration number 302012038338) for @T.E.L.L. While company promoters have claimed that it may from now on be illegal for other commercial interests to use the At-sign, this only applies to identical or confusingly similar goods  and no court, German or otherwise, has yet ruled on this purported illegality.
A common contemporary use of @ is in email addresses (transmitted by SMTP), as in email@example.com (the user jdoe located at site the example.com domain). BBN Technologies' Ray Tomlinson is credited with introducing this usage in 1971. This idea of the symbol representing located at in the form user@host is also seen in other tools and protocols; for example, the Unix shell command ssh firstname.lastname@example.org tries to establish an ssh connection to the computer with the hostnameexample.net using the username jdoe.
On web pages, organizations often obscure email addresses of their members or employees by omitting the @. This practice, known as address munging, makes the email addresses less vulnerable to spam programs that scan the internet for them.
Another contemporary use of the @ symbol in American English is adding information about a sporting event. Opposing sports teams sometimes have their names separated by a v. (for versus). However, the "v." may be replaced with "@" when also conveying at which team's home field the game will be played. In this case, the away team is written first.
On some online forums without threaded discussions, @ is used to denote a reply; for instance: "@Jane" to respond to a comment Jane made earlier. Similarly, in some cases, @ is used for "attention" in email messages originally sent to someone else. For example, if an email was sent from Catherine to Steve, but in the body of the email, Catherine wants to make Keirsten aware of something, Catherine will start the line "@Keirsten" to indicate to Keirsten that the following sentence concerns her. This also helps with mobile email users who cannot see bold or color in email.
In microblogging (such as Twitter and StatusNet-based microblogs), @ before the user name is used to send publicly readable replies (e.g. "@otheruser: Message text here"). The blog and client software can automatically interpret these as links to the user in question. This use of the @ symbol was also made available to Facebook users on September 15, 2009. In Internet Relay Chat (IRC), it is often shown before a user's nick to mark the operator of a channel.
@ is also used on many wireless routers/modems, where a solid green @ symbol indicates the router is connected and a solid amber @ indicates there is a problem.
@ is used in various programming languages although there is not a consistent theme to its usage. For example:
In ALGOL 68, the @ symbol is brief form of the at keyword; it is used to change the lower bound of an array. For example: arrayx[@88] now refers to an array starting at index 88.
In ActionScript, @ is used in XML parsing and traversal as a string prefix to identify attributes in contrast to child elements.
In C#, it denotes "verbatim strings", where no characters are escaped and two double-quote characters represent a single double-quote. As a prefix it also allows keywords to be used as identifiers.
In the ASP.NET MVCRazor template markup syntax, the @ character denotes the start of code statement blocks or the start of text content.
In Forth, it is used to fetch values from the address on the top of the stack. The operator is pronounced as "fetch".
In Haskell, it is used in so-called as-patterns. This notation can be used to give aliases to patterns, making them more readable.
In Java, it has been used to denote annotations, a kind of metadata, since version 5.0.
In several xBase-type programming languages, like DBASE, FoxPro/Visual FoxPro and Clipper, it is used to denote position on the screen. For example: @1,1 SAY "HELLO" to show the word "HELLO" in line 1, column 1.
In Portuguese and Spanish, as well in other West Iberian languages where many words end in '-o' when in the masculine gender and end '-a' in the feminine, @ can be used as a gender-neutral substitute for the default 'o' ending, which some advocates of gender-neutral language-modification feel indicates implicit linguistic disregard for women. These languages do not possess a neutral gender and the masculine forms are also used traditionally when referring to groups of mixed or unknown sex. The at-sign is intended to replace the desinence '-o', including its plural form '-os', due to the resemblance to a digraph of an inner letter 'a' and an outer letter 'o'.
As an example of the @ being used for gender-inclusive purposes, we can consider the Spanish and Portuguese word amigos. When the word represents not only male friends, but also female ones, the proponents of a gender-inclusive language replace it with amig@s. In this sense, amigos would be used only when the writer is sure the group referred to is all-male. Usage of amigas is the same in traditional and such new forms of communication. Alternative forms for a gender-inclusive at-sign would be the slash sign (amigos/as) and the circle-A, (amigⒶs). However, it is more common to use the masculine ending first and include the feminine in parentheses, as in amigos(as). For more about this, see Satiric misspelling.
In (especially English) scientific and technical literature, @ is used to describe the conditions under which data are valid or a measurement has been made. E.g. the density of saltwater may read d = 1.050 g/cm³ @ 15°C (read "at" for @), density of a gas d = 0,150 g/L @ 20°C, 1 bar, or noise of a car 81 dB @ 80 km/h (speed).
As an abbreviation for alias in articles about missing persons, obituaries, brief reports - for instance: "John Smith @ Jean Smyth" (a possible abbreviation of aka). For example, a Chinese Singaporean may use two transliterations of his or her Chinese name (e.g., Mao Tse-Tung @ Mao Zedong).
It is frequently used in typing and text messaging as an abbreviation for "at".
In Portugal and Brazil, it may be used in typing and text messaging with the meaning "french kiss" (linguado).
In online discourse, @ is used by some anarchists as a substitute for the traditional circle-A.
Names in other languages
In many languages other than English, although most typewriters included the symbol, the use of @ was less common before email became widespread in the mid-1990s. Consequently, it is often perceived in those languages as denoting "the Internet", computerization, or modernization in general.
In Afrikaans, it is called aapstert, meaning "monkey tail", similarly to the Dutch use of the word.
In mainland China, it is quan A (圈A), meaning "circled A / enclosed A" or hua A (花A), meaning "lacy A". Sometimes as xiao laoshu (小老鼠), meaning "little mouse". Nowadays, for most of China's youth, it is at.
In Taiwan, it is xiao laoshu (小老鼠), meaning "little mouse".
In Croatian, it is most often referred to by the English word "at". Informally, it is called a manki, coming from the local pronunciation of the English word "monkey". Note that the Croatian word for monkey, majmun, is not used to denote the symbol.
In Danish, it is snabel-a ("[elephant's] trunk A").
In Dutch, it is called apenstaartje ("[little] monkeytail"). However, the use of the English ´at´ has been coming increasingly populair in Dutch.
In Esperanto, it is called ĉe-signo ("at" – for the email use, with an address like "email@example.com" pronounced zamenhof ĉe esperanto punkto org), po-signo ("each" – refers only to the mathematical use), or heliko (meaning "snail").
in Estonian, it is called at, from the English word.
In Faroese, it is kurla, hjá ("at"), tranta, or snápil-a ("[elephant's] trunk A").
In Finnish, it was originally called taksamerkki ("fee sign") or yksikköhinnan merkki ("unit price sign"), but these names are long obsolete and now rarely understood. Nowadays, it is officially ät-merkki, according to the national standardization institute SFS; frequently also spelled "at-merkki". Other names include kissanhäntä ("cat's tail") and miukumauku ("miaow-meow").
In French, it is now officially the arobase (also spelled arrobase or arrobe), or a commercial (though this is most commonly used in French-speaking Canada, and should normally only be used when quoting prices; it should always be called arobase or, better yet, arobas when in an email address). Its origin is the same as that of the Spanish word, which could be derived from the Arabicar-roub. In France, it is also common (especially for younger generations) to say the English word "at" when spelling out an email address.
In Georgian, it is at, spelled ეთ–ი (კომერციული ეთ–ი).
In German, it has sometimes been referred to as Klammeraffe (meaning "spider monkey"). Klammeraffe refers to the similarity of @ to the tail of a monkey grabbing a branch. Lately, it has mostly been called at, just like in English.
In Greek, it is most often referred to as παπάκι (papaki), meaning "duckling", due to the similarity it bears with comic character designs for ducks.
In Greenlandic, and Inuit language, it is called aajusaq meaning "A-like" or "something that looks like A".
In Hebrew, it is colloquially known as שטרודל (shtrudel), due to the visual resemblance to a cross-section cut of a strudel. The normative term, invented by The Academy of the Hebrew Language, is כרוכית (krukhit), which is another Hebrew word for "strudel".
In Hungarian, it is called kukac ("worm", "maggot").
In Icelandic, it is referred to as atmerkið ("at sign") or hjá, which is a direct translation of the English word "at".
In Indian English, speakers often say at the rate of (with e-mail addresses quoted as "example at the rate of example.com").
In Indonesian, it is usually et. Variations exist – especially if verbal communication is very noisy – such as a bundar and a bulat (both meaning "circled A"), a keong ("snail A"), and (most rarely) a monyet ("monkey A").
In Irish, it is ag (meaning "at") or comhartha @/ag (meaning "at sign").
In Italian, it is chiocciola ("snail") or a commerciale, sometimes at (pronounced more often [ˈɛt] and rarely [ˈat]) or ad.
In Kazakh, it is officially called айқұлақ ("moon's ear"), sometimes unofficial as ит басы ("dog's head").
In Korean, it is called golbaeng-i (골뱅이, meaning "bai top shells"), a dialectal form of whelk.
In Kyrgyz, it is officially called маймылча ("monkey"), sometimes unofficially as собачка ("doggy"), and et.
In Latvian, it is pronounced the same as in English, but, since in Latvian [æ] is written as "e" (not "a" as in English), it is sometimes written as et.
In Lithuanian, it is eta (equivalent to the English "at" but with a Lithuanian ending).
In Luxembourgish it used to be called Afeschwanz ("monkey tail"), but due to widespread use, it is now called at, like in English.
In Macedonian, it is called мајмунче (my-moon-cheh – "little monkey").
In Malay, it is called alias when it is used in names and di when it is used in email addresses. It is also commonly used to abbreviate atau which means "or" or "either".
In Morse code (not a language), it is known as a "commat", consisting of the Morse code for the "A" and "C" which run together as one character: ·--·-·. The symbol was added in 2004 for use with email addresses, the only official change to Morse code since World War I.
In Norwegian, it is officially called krøllalfa ("curly alpha" or "alpha twirl"). (The alternate alfakrøll is also common, but is not its official name.) Sometimes snabela, the Swedish/Danish name (which means "trunk A", as in "elephant's trunk"), is used. Commonly, people will call the symbol [æt] (as in English), particularly when giving their email addresses.
In The Philippines, at means "and" in Tagalog, which could be used interchangeably in colloquial abbreviations. Ex: magluto @ kumain ("cook and eat").
In Polish, it is called, both officially and commonly, małpa ("monkey"), and sometimes małpka ("little monkey").
In Portuguese, it is called arroba (from the Arabic arrub). The word "arroba" is also used for a weight measure in Portuguese. One arroba is equivalent to 32 old Portuguese pounds, approximately 14.7 kg, and both the weight and the symbol are called arroba. In Brazil, cattle are still priced by the arroba – now rounded to 15 kg. (This occurs because the same sign was used to represent the same measure.)
In Romanian, it is most commonly called at, but also colloquially called Coadă de maimuţă ("monkey tail") or a-rond. The latter is commonly used, and it comes from the word "round" (from its shape), but that is nothing like the mathematical symbol A-rond (rounded A). Others call it aron, or la.
In Russian, it is most commonly собака (sobaka, meaning "dog"). The name "dog" has come from Soviet computers DVK where the symbol had a short tail and similarity to a dog.
In Serbian, it is called лудо А (ludo A – "crazy A"), мајмунче (majmunče – "little monkey"), or мајмун (majmun – "monkey").
In Slovak, it is called zavináč ("pickled fish roll").
In Slovenian, it is called afna ("little monkey").
In Spanish-speaking countries, it denotes a pre-metric unit of weight. While there are regional variations in Spain and Mexico, it is typically considered to represent approximately 25 pounds (11.5 kg), and both the weight and the symbol are called arroba. It has also been used as a unit of volume for wine and oil and recently to denote masculine and feminine gender in the same word (masculine amigos; feminine amigas; neuteramig@s).
In Swedish, it is called snabela ("[elephant's] trunk A") or simply at, like in the English language.
In Swiss German, it is commonly called Affenschwanz ("monkey-tail"). However, the use of the English ´at´ has been coming increasingly popular in German.
In Thai, it is commonly called at, like in English.
In Turkish, it is commonly called et, like in English but written in Turkish letters.
In Ukrainian, it is commonly called ет (et – "at"), other names being равлик (ravlyk – "snail"), слимачок (slymachok – "little slug"), вухо (vukho – "ear"), and песик (pesyk – "little dog").
John Lloyd, pledged on QI series A DVD to support widespread use of the term "Astatine" to refer to the symbol. This name was chosen as the chemical element astatine has the chemical symbol "At".
American R&B singer Usher used a version of the at sign in his career, where the "a" was replaced with the vowel "u" from his name. Puerto Rican artist Miguelito also uses his version of the at sign where the "a" is replaced by the letter "m" from his name in his own line of merchandise that includes clothes, school supplies, his studio albums, etc.
In the 1980 Video GameRogue, presented in ASCII graphics, the player character is represented by the @. Many similar games, called Roguelikes, use the same presentation, and traditionally use the @ to represent the player character as well.