At sign

The at sign is a typographical symbol used as an accounting and invoice abbreviation meaning "at a rate of", and now seen more widely in email addresses and social media platform handles. In English, it is normally read aloud as "at", and is also commonly called the at symbol, commercial at , or address sign. Most languages have [|their own name] for the symbol.
Although not included on the keyboard layout of the earliest commercially successful typewriters, it was on at least one 1889 model and the very successful Underwood models from the "Underwood No. 5" in 1900 onward. It started to be used in email addresses in the 1970s, and is now routinely included on most types of computer keyboards.

History

The earliest yet discovered symbol in this shape is found in a 1345 Bulgarian translation of a Greek chronicle written by Constantinos Manasses. Held today in the Vatican Apostolic Library, the initial letter of the word амин looks like an at sign.
The symbol has long been used in Catalan, Spanish and Portuguese as an abbreviation of arroba, a unit of weight equivalent to 25 pounds, and derived from the Arabic expression of "the quarter". A symbol resembling an @ is found in the Spanish "Taula de Ariza", a registry to denote a wheat shipment from Castile to Aragon, in 1448. The historian Giorgio Stabile reports having traced the @ symbol to the 16th century, in a mercantile document sent by Florentine Francesco Lapi from Seville to Rome on May 4, 1536, stating that the symbol was interpreted to mean amphora, a unit of weight and volume based upon the capacity of the standard amphora jar since the 6th century. The document is about commerce with Pizarro, in particular the price of an @ of wine in Peru.
The symbol could also mean adi as used on a health pass in Northern Italy in 1667.
In 2010, the Museum of Modern Art added the @ symbol to its design collection. In 2025, it was also included in MoMA's Pirouette: Turning Points in Design, an exhibition of "widely recognized design icons highlighting pivotal moments in design history," alongside the I ♥ NY logo, Google map pins, and original 1980s Mac GUI icons, and the NASA Worm insignia.

Name

The name of the symbol arises from its original use in showing quantities and their price per unit for example, "10 widgets @ £1.50 each". The precise origin of the symbol is uncertain.
The absence of a single English word for the symbol has prompted some writers to use the French arobase, to coin new words such as ampersat and asperand, or to use the onomatopoeia strudel, but none of these have achieved wide use.

Modern use

Commercial usage

In contemporary English usage, @ is a commercial symbol, meaning at and at the rate of or at the price of. It has rarely been used in financial ledgers, and is not used in standard typography.

Trademark

In 2012, "@" was registered as a trademark with the German Patent and Trade Mark Office. A cancellation request was filed in 2013, and the cancellation was ultimately confirmed by the German Federal Patent Court in 2017.

Email addresses

A common contemporary use of @ is in email addresses, as in jdoe@example.com. Ray Tomlinson of BBN Technologies is credited for having introduced 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, it's used in some command-line utilities that connect to a remote host, such as Secure Shell.
On web pages, organizations often obscure the email addresses of their members or employees by omitting the @. This practice, known as address munging, attempts to make the email addresses less vulnerable to spam programs that scan the internet for them.

Social media

On many social media platforms and forums, usernames or handles prefixed with an @ are interpreted as mentions of that user and may be treated specially.
On online forums without threaded discussions, @ is commonly 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 to signal to Keirsten that the following sentence concerns her. This also helps with mobile email users who might not see bold or color in email.
In microblogging, an @ before the user name is used to send publicly readable replies. The blog and client system interpret these as links to the user in question. When included as part of a person's or company's contact details, an @ symbol followed by a name is normally understood to refer to a Twitter handle. A similar use of the @ symbol was added to Facebook on September 15, 2009. In Internet Relay Chat, it is shown before users' nicknames to denote they have operator status on a channel.

Computer languages

@ is used in various programming languages and other computer languages, although there is not a consistent theme to its usage. For example:

In ActionScript, @ is used in XML parsing and traversal as a string prefix to identify attributes in contrast to child elements.
In Ada 2022, @ is the target name symbol, an abbreviation of the LHS of an assignment; it is used to avoid repetition of potentially long names in assignment statements. For example: A_Very_Long_Variable_Name := A_Very_Long_Variable_Name + 1; is shortened to A_Very_Long_Variable_Name := @ + 1;, increasing readability.
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: refers to an array starting at index 88.
In Dyalog APL, @ is used as a functional way to modify or replace data at specific locations in an array.
In the ASP.NET MVC Razor template markup syntax, the @ character denotes the start of code statement blocks or the start of text content.
In Assembly language, @ is sometimes used as a dereference operator.
In CSS, @ is used in special statements outside of a CSS block.
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, a form of stropping.
In D, it denotes function attributes: like: @safe, @nogc, user defined @ which can be evaluated at compile time or @property to declare properties, which are functions that can be syntactically treated as if they were fields or variables.
In DIGITAL Command Language, the @ character was the command used to execute a command procedure. To run the command procedure VMSINSTAL.COM, one would type @VMSINSTAL at the command prompt.
In the Domain Name System, @ is used to represent the, typically the "root" of the domain without a prefixed sub-domain.
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 HTML, it can be encoded as &commat;
In J, denotes function composition.
In Java, it has been used to denote annotations, a kind of metadata, since version 5.0.
In Julia, it denotes the invocation of a macro.
In LiveCode, it is prefixed to a parameter to indicate that the parameter is passed by reference.
In an LXDE autostart file, @ is prefixed to a command to indicate that the command should be automatically re-executed if it crashes.
In a Makefile, @ specifies to not output the command before it is executed.
In ML, it denotes list concatenation.
In modal logic, specifically when representing possible worlds, @ is sometimes used as a logical symbol to denote the actual world.
In Objective-C, @ is prefixed to language-specific keywords such as @implementation and to form string literals.
In InterSystems ObjectScript, @ is the indirection operator, enabling dynamic runtime substitution of part or all of a command line, a command, or a command argument.
In Pascal, @ is the "address of" operator.
In Perl, @ prefixes variables which contain arrays, including array slices and hash slices or. This use is known as a sigil.
In PHP, it is used just before an expression to make the interpreter suppress errors that would be generated from that expression.
In Python 2.4 and up, it is used to decorate a function. In Python 3.5 and up, it is also used as an overloadable matrix multiplication operator.
In R and S-PLUS, it is used to extract slots from S4 objects.
In Razor, it is used for C# code blocks.
In Ruby, it functions as a sigil: @ prefixes instance variables, and @@ prefixes class variables.
In Rust, it is used to bind values matched by a pattern to a variable.
In Scala, it is used to denote annotations, and also to bind names to subpatterns in pattern-matching expressions.
In Swift, @ prefixes "annotations" that can be applied to classes or members. Annotations tell the compiler to apply special semantics to the declaration like keywords, without adding keywords to the language.
In T-SQL, @ prefixes variables and @@ prefixes "niladic" system functions.
In several xBase-type programming languages, like DBASE, FoxPro/Visual FoxPro and Clipper, it is used to denote position on the screen. For example: to show the word "HELLO" in line 1, column 1.
* In FoxPro/Visual FoxPro, it is also used to indicate explicit pass by reference of variables when calling procedures or functions.
In a Windows Batch file, an @ at the start of a line suppresses the echoing of that command. In other words, is the same as ECHO OFF applied to the current line only. Normally a Windows command is executed and takes effect from the next line onward, but @ is a rare example of a command that takes effect immediately. It is most commonly used in the form which not only switches off echoing but prevents the command line itself from being echoed.
In Windows PowerShell, @ is used as array operator for array and hash table literals and for enclosing here-string literals.
The Vue template language uses @ as a short-hand for the v-on event handler directive