The dollar sign, also known as peso sign, is a currency symbol consisting of a capital "S" crossed with one or two vertical strokes ($ or depending on typeface), used to indicate the unit of various currencies around the world, including most currencies denominated "peso" and "dollar". The explicitly double-barred sign is called cifrão in the Portuguese language.
The sign is also used in several compound currency symbols, such as the Brazilian real (R$) and the United States dollar (US$): in local use, the nationality prefix is usually omitted. In countries that have other currency symbols, the US dollar is often assumed and the "US" prefix omitted.
The one- and two-stroke version are often considered mere stylistic (typeface) variants, although in some places and epochs one of them may have been specifically assigned, by law or custom, to a specific currency. The Unicode computer encoding standard defines a single code for both.
In most English-speaking countries that use that symbol, it is placed to the left of the amount specified, e.g. "$1", read as "one dollar".
History
Use for the Spanish American peso in the late 1700s
The symbol appears in business correspondence in the 1770s from Spanish America, the early independent U.S., British America and Britain, referring to the Spanish American peso,[1][2] also known as "Spanish dollar" or "piece of eight" in British America. Those coins provided the model for the currency that the United States adopted in 1792, and for the larger coins of the new Spanish American republics, such as the Mexican peso, Argentine peso, Peruvian real, and Bolivian sol coins.
The earliest U.S. dollar coins did not have any dollar symbol. The first occurrence in print is claimed to be from 1790s, by a Philadelphia printer Archibald Binny, creator of the Monticello typeface.[6] The $1 United States Note issued by the United States in 1869 included a large symbol consisting of a "U" with the right bar overlapping an "S" like a single-bar dollar sign, as well as a very small double-stroke dollar sign in the legal warning against forgery.[7]
Earlier history of the symbol
A piece of eight from the Potosí mint, showing the Pillars of Hercules with "S" ribbons, and two "PTSI" monograms at about 4 and 8 o'clock around the edge
It is still uncertain, however, how the dollar sign came to represent the Spanish American peso. There are currently several competing hypotheses:
The most widely accepted theory holds that the sign grew out of the Spanish and Spanish American scribal abbreviation "ps" for pesos. A study of late 18th- and early 19th-century manuscripts shows that the s gradually came to be written over the p, developing into a close equivalent to the "$" mark.[8][9][10][11][12]Oliver Pollock, a wealthy Irish trader and early supporter of the American Revolution, used the abbreviation "ps", sometimes run together in a way that almost exactly resembled the dollar sign, in a letter dated 1778.[6][13] There are documents showing the common use of the two-stroke version in Portugal already by 1775.[14]
Another hypothesis derives the sign from a depiction of the Pillars of Hercules, a classical symbol for two sides of the Strait of Gibraltar, with a ribbon wrapped around each pillar (or both pillars) in the form of an "S". This device is a support element of the Spanish coat of arms, and appeared on the most common real de ocho coins circulating at the time in the Americas and Europe; namely, those minted at the Potosí mint in Bolivia, which operated from 1573 to 1825.[15][10] Indeed, one of the names used for Spanish dollars in Qing Dynasty China was 雙柱; Shuāngzhù; 'double-pillar'.[16]
A variant of the above theory claims that the sign comes from the mark of the mint at Potosí, where a large portion of the Spanish Empire's silver was mined. A feature on these coins were the letters "P T S I" superimposed. The core of this monogram is a (single-stroked) "$" sign.[17]
Sample ledger with a sign for dollar from John Collins 1686
Yet another hypothesis notes that the English word "dollar" for the Spanish piece of eight originally came (through Dutchdaalder) from Joachimsthaler or thaler, a similar large German silver coin which was widely used in Europe. It is therefore conjectured that the dollar sign derived from a symbol consisting of a superimposing S and I or J that was used to denote the German silver coin. Such symbol appears in the 1686 edition of An Introduction to Merchants' Accounts by John Collins.[18] Alternatively, the symbol could have come from a snake and cross emblem on the thaler coins.[6]
Less likely theories
The following theories seem to have been discredited or contradicted by documentary evidence:
In 1937, historian James Alton James claimed that the symbol with two strokes was an adapted design of patriot Robert Morris in 1778, in letters written to Pollock.[19][20][13]
In 1939, H. M. Larson suggested that the sign could derive from a combination of the Greek character "psi" (ψ) and "S".[21]
A theory claims that the sign started off as a monogram of "US", with a narrow "U" superimposed on the "S"; the bottom part of the "U" would have been lost, producing the dollar sign with two vertical lines. This theory was mentioned in letters to Notes and Queries in 1876.[8]Henry Towne begins his classic 1886 essay on management with this theory.[22] This was also claimed by Ayn Rand in her 1957 book Atlas Shrugged; in her version of the theory the monogram "US" would have been used on money bags issued by the United States Mint.[23][6]
Authors T. Seijas and J. Frederick noted that the captors of slaves in Spanish territories sometimes branded enslaved people with a symbol very similar to a one-barred dollar sign. Esclavo is Spanish for "slave," and clavo means nail. A dollar sign would then be S + clavo.[15]
A theory often cited in Portuguese speaking countries is that the "S" part of the doubly-stroked sign is a schematic representation of the path followed by the Umayyad Caliphate general Tariq Ibn Ziyad in his conquest of the Visigoth kingdom in 711 CE, and the two strokes represent the Pillars of Hercules that he would have crossed along that path. That symbol would have been engraved in coins commemorating his victory, and then became symbolic of currency in general.[24]
Currencies that use the dollar sign
As symbol of the currency
The numerous currencies called "dollar" use the dollar sign to express money amounts. The sign is also generally used for the many currencies called "peso" (except the Philippine peso, which uses the symbol "₱"). Within a country the dollar/peso sign may be used alone. In other cases, and to avoid ambiguity in international usage, it is usually combined with other glyphs, e.g. CA$ or Can$ for Canadian dollar. Particularly in professional contexts, the unambiguous ISO 4217 three letter code (AUD, MXN, USD, etc.) is preferred.
The dollar sign, alone or in combination with other glyphs, is or was used to denote several currencies with other names, including:
Brazilian cruzeiro (various currencies, all defunct): ₢$, CR, Cr, NCr etc.
In the United States, Mexico, Australia, Argentina, Chile, New Zealand, Hong Kong, Pacific Island nations, and English-speaking Canada, the sign is written before the number ("$5"), even though the word is written or spoken after it ("five dollars", "cinco pesos"). In French-speaking Canada, exceptionally, the dollar symbol usually appears after the number,[25] e.g., "5$". (The cent symbol is written after the number in most countries that use it, e.g., "5¢".)
Use in the Portuguese Empire
Car for sale in Cape Verde, showing use of the cifrão as decimals separator
In Portugal, Brazil, and other parts of the Portuguese Empire, the two-stroke variant of the sign (with the name cifrão; (Portuguese pronunciation:[siˈfɾɐ̃w]ⓘ) was used as the thousands separator of amounts in the national currency, the real (plural "réis", abbreviated "Rs."): 123500 meant "123500 réis". This usage is attested in 1775, but may be older by a century or more.[14] It is always written with two vertical lines: . It is the official sign of the Cape Verdean escudo (ISO 4217: CVE).
In 1911 Portugal redefined the national currency as the escudo, worth 1000 réis, and divided into 100 centavos; but the cifrão continued to be used as the decimal separator,[26] so that 12350 meant 123.50 escudos or 123 escudos and 50 centavos. This usage ended in 2002 when the country switched to the euro. (A similar scheme to use a letter symbol instead of a decimal point is used by the RKM code in electrical engineering since 1952.)
Cape Verde, a republic and former Portuguese colony, similarly switched from the real to their local escudo and centavos in 1914, and retains the cifrão usage as decimals separator as of 2021. Local versions of the Portuguese escudo were for a time created also for other overseas colonies, including East Timor (1958–1975), Portuguese India (1958–1961), Angola (1914–1928 and 1958–1977), Mozambique (1914–1980), Portuguese Guinea (1914–1975), and São Tomé and Príncipe (1914–1977); all using the cifrão as decimals separator.[citation needed]
Brazil retained the real and the cifrão as thousands separator until 1942, when it switched to the Brazilian cruzeiro, with comma as the decimals separator. The dollar sign, officially with one stroke but often rendered with two, was retained as part of the currency symbol "Cr $", so one would write Cr$13,50 for 13 cruzeiros and 50 centavos.[27]
In some places and at some times, the one- and two-stroke variants have been used in the same contexts to distinguish between the U.S. dollar and other local currency, such as the former Portuguese escudo.[26]
However, such usage is not standardized, and the Unicode specification considers the two versions as graphic variants of the same symbol—a typeface design choice.[31] Computer and typewriter keyboards usually have a single key for that sign, and many character encodings (including ASCII and Unicode) reserve a single numeric code for it. Indeed, dollar signs in the same digital document may be rendered with one or two strokes, if different computer fonts are used, but the underlying codepoint U+0024 (ASCII 3610) remains unchanged.
When a specific variant is not mandated by law or custom, the choice is usually a matter of expediency or aesthetic preference. Both versions were used in the US in the 18th century. (An 1861 Civil War-era advertisement depicts the two-stroked symbol as a snake.[13]) The two-stroke version seems to be generally less popular today, though used in some "old-style" fonts like Baskerville.
Use in computer software
Because of its use in early American computer applications such as business accounting, the dollar sign is almost universally present in computer character sets, and thus has been appropriated for many purposes unrelated to money in programming languages and command languages.
Encoding
The dollar sign "$" has Unicode code point U+0024 (inherited from ASCII via Latin-1).[31]
There are no separate encodings for one- and two-line variants. The choice is typeface-dependent, they are allographs. However, there are three other code points that originate from other East Asian standards: the Taiwanese small form variant, the CJK fullwidth form, and the Japanese emoji. The glyphs for these code points are typically larger or smaller than the primary code point, but the difference is mostly aesthetic or typographic, and the meanings of the symbols are the same.
U+FE69﹩SMALL DOLLAR SIGN
U+FF04＄FULLWIDTH DOLLAR SIGN
U+1F4B2💲HEAVY DOLLAR SIGN
However, for usage as the special character in various computing applications (see following sections), U+0024 is typically the only code that is recognized.
Support for the two-line variant varies. As of 2019,[update] the Unicode standard considers the distinction between one- and two-bar dollar signs a stylistic distinction between fonts, and has no separate code point for the cifrão. The symbol is not in the October 2019 'pipeline',[34] though it has been requested formally.[26]
In LaTeX, with the textcomp package installed, the cifrão () can be input using the command \textdollaroldstyle. However, because of font substitution and the lack of a dedicated code point, the author of an electronic document who uses one of these fonts intending to represent a cifrão cannot be sure that every reader will see a double-bar glyph rather than the single barred version. Because of the continued lack of support in Unicode, a single bar dollar sign is frequently employed in its place even for official purposes.[29][35] Where there is any risk of misunderstanding, the ISO 4217 three-letter acronym is used.
Programming languages
$ was used for defining stringvariables in older versions of the BASIC language, e.g. CHR$ ($ was often pronounced "string" instead of "dollar" in this use).
$ is prefixed to names to define variables in the PHP language and the AutoIt automation script language, scalar variables in the Perl language (see sigil (computer programming)), and global variables in the Ruby language. In Perl programming this includes scalar elements of arrays$array[7] and hashes$hash{foo}.
In most shell scripting languages, $ is used to indicate the insertion into strings of environment variables, special variables, input data fields, previous commands, arithmetic computations, and special characters, and for performing translation of localised strings. In the shell script languages of CP/M, DOS, and several Unix-like systems, it is used to insert variable information (such as the current working directory, user name, or sequential command number) in the command prompt.
$ is used for defining hexadecimal constants in Pascal-like languages such as Delphi, and in some variants of assembly language.
$ is used in the TeXtypesetting language to delimit mathematical regions.
In many versions of FORTRAN 66, $ could be used as an alternative to a quotation mark for delimiting strings.
In PL/M, $ can be used to put a visible separation between words in compound identifiers. For example, Some$Name refers to the same thing as 'SomeName'.
In Haskell, $ is used as a function application operator.
In an AutoHotkey script, a hotkey declared with $ is not triggered by a 'Send' command elsewhere in the script.
In JavaScript from ES6 onward it is used inside template literals to insert the value of a variable. For example, if varword="such" then `as ${word}` would equal 'as such'.
In several JavaScript frameworks such as Prototype.js and jQuery, $ is a common utility class, and is often referred to as the buck.[citation needed] Otherwise, it's a character allowed in identifiers.
In ASP.NET, the dollar sign used in a tag in the web page indicates an expression will follow it. The expression that follows is .NET language-agnostic, as it will work with C#, VB.NET, or any CLR supported language.
In Erlang, the dollar sign precedes character literals. The dollar sign as a character can be written $$.
In COBOL the $ sign is used in the Picture clause to depict a floating currency symbol as the left most character. The default symbol is $; however, if the CURRENCY= or CURRENCY SIGN clause is specified, many other symbols can be used.
In Sass, the $ sign is prefixed to define a variable.
In Svelte, the $ sign can be used to mark reactive statements.
In Python, although you'll not come across the $ sign operator when learning about operators in Python, you can use the $ sign to format strings using the string template class.
Operating systems
In CP/M and subsequently in all versions of DOS (86-DOS, MS-DOS, PC DOS, more) and derivatives, $ is used as a string terminator (Int 21h with AH=09h).
In Microsoft Windows, $ is appended to the share name to hide a shared folder or resource. For example, \\server\share will be visible to other computers on a network, while \\server\share$ will be accessible only by explicit reference. Hiding a shared folder or resource will not alter its access permissions but may render it inaccessible to programs or other functions which rely on its visibility. Most administrative shares are hidden in this way.
In the LDAP directory access protocol, $ is used as a line separator in various standard entry attributes such as postalAddress.
In the UNIVAC EXEC 8 operating system, $ means "system". It is appended to entities such as the names of system files, the "sender" name in messages sent by the operator, and the default names of system-created files (like compiler output) when no specific name is specified (e.g., TPF$, NAME$, etc.)
In RISC OS, $ is used in system variables to separate the application name from the variables specific to that application. For example Draw$Dir specifies the directory where the !Draw application is located. It is also used to refer to the root directory of a file system.
Applications
Microsoft Excel[36] and other spreadsheet software use the dollar sign ($) to denote a fixed row, fixed column reference, or an absolute cell reference.
$ matches the end of a line or string in sed, grep, and POSIX and Perlregular expressions, as well as the end of a line or the file in text editors ed, ex, vi, pico, and derivatives.
Other uses
The symbol is sometimes used derisively, in place of the letter S, to indicate greed or excess money such as in "Micro$oft", "Di$ney", "Chel$ea" and "GW$"; or supposed overt Americanisation as in "$ky". The dollar sign is also used intentionally to stylize names such as A$AP Rocky, Ke$ha, and Ty Dolla $ign or words such as ¥€$. In 1872, Ambrose Bierce referred to California governor Leland Stanford as $tealand Landford.[37]
In Scrabble notation, a dollar sign is placed after a word to indicate that it is valid according to the North American word lists, but not according to the British word lists.[38]
A dollar symbol is used as unit of reactivity for a nuclear reactor, 0 $ being the threshold of slow criticality, meaning a steady reaction rate, while 1 $ is the threshold of prompt criticality, which means a nuclear excursion or explosion.[39][40]
^ abNussbaum, Arthur (1957). A History of the Dollar. New York: Columbia University Press. p. 56. The foreign coins remained in circulation [in the United States], and the more important among them, especially the Spanish (including the Mexican) dollars, were declared by Congress on February 9, 1793, to be legal tender. The dollar sign, $, is connected with the peso, contrary to popular belief, which considers it to be an abbreviation of 'U.S.' The two parallel lines represented one of the many abbreviations of 'P,' and the 'S' indicated the plural. The abbreviation '$.' was also used for the peso, and is still used in Argentina.
^ abJoão Joseph Du Beux (1775): Receipt of 270$000 Rs.Archived 12 August 2021 at the Wayback Machine for purchase by of 50 volumes of the Acta Santorum by the College of the Carmo of Coimbra. Quote: "Recebemos [...] a quantia de Duzentos Settenta mil reis[...] por Clareza passamos este Coimbra 15 de Março de 1775. São 270000 Rs". Cartório do Colégio do Carmo, Maço 35, n.o 17. apud ALMEIDA, Manuel Lopes in "Livro, livreiros, impressores em documentos da Universidade", Arquivo de Bibliografia Portuguesa, ano X–XII, Atlântida, Coimbra, 1964–66, n o 37–48.
^ abSeijas, Tatiana and Jake Frederick (2017). Spanish Dollars and Sister Republics: The Money That Made Mexico and the United States. Lanham: Rowman & Littlefield. pp. 3–4. ISBN9781538100462.
^James, James Alton (1929). "'Robert Morris, Financier of the Revolution in the West'". The Mississippi Valley Historical Review.
^Larson, Henrietta M. (October 1939). "Note on Our Dollar Sign". Bulletin of the Business Historical Society. 13 (4): 57–58. doi:10.2307/3111350. JSTOR3111350.
^Towne, Henry R. (1886). “Engineer as an Economist”. in Transactions of the American Society of Mechanical Engineers, New York City: American Society of Mechanical Engineers.
^(1960): Price "Cr$ 15,00" on the front coverArchived 14 August 2021 at the Wayback Machine of the 1960-05-07 issue of O Cruzeiro magazine, reproduced on the Muzeez website on 2016-12-105. Accessed on 2021-08-14.
^"24 Character entity references in HTML 4". www.w3.org. Archived from the original on 1 April 2018. Retrieved 7 April 2018. The following sections present the complete lists of character entity references
Category
depending on typeface), used to indicate the unit of various currencies around the world, including most currencies denominated "peso" and "dollar". The explicitly double-barred 
