Dollar sign

The dollar sign, also known as the 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 "dollar" or "peso". 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 versions 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".
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, 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.
With the Coinage Act of 1792, the United States Congress created the U.S. dollar, defining it to have "the value of a Spanish milled dollar as the same is now current" but a variety of foreign coins were deemed to be legal tender until the Coinage Act of 1857 ended this status.
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. The $1 United States Note issued by the United States in 1869 included a large symbol consisting of a "U" with the right bar overlapping an "S" like a single-bar dollar sign, as well as a very small double-stroke dollar sign in the legal warning against forgery.
It is still uncertain, however, how the dollar sign came to represent the Spanish American peso. There are currently several competing hypotheses:
The following theories seem to have been discredited or contradicted by documentary evidence:
The numerous currencies called "dollar" use the dollar sign to express money amounts. The sign is also generally used for the many currencies called "peso" (except the Philippine peso, which uses the symbol "₱"). Within a country the dollar/peso sign may be used alone. In other cases, and to avoid ambiguity in international usage, it is usually combined with other glyphs, e.g. CA$ 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:
In the United States, Mexico, Australia, Argentina, Chile, Colombia, New Zealand, Hong Kong, Pacific Island nations, and English-speaking Canada, the sign is written before the number ("$5"), even though the word is written or spoken after it ("five dollars", "cinco pesos"). In French-speaking Canada, exceptionally, the dollar symbol usually appears after the number, e.g., "5$". (The cent symbol is written after the number in most countries that use it, e.g., "5¢".)
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. 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, 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.
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.
The cifrão was formerly used by the Portuguese escudo (ISO: PTE) before its replacement by the euro and by the Portuguese Timor escudo (ISO: TPE) before its replacement by the Indonesian rupiah and the US dollar. In Portuguese and Cape Verdean usage, the cifrão is placed as a decimal point between the escudo and centavo values. The name originates in the Arabic ṣifr (‏صِفْر‎), meaning 'zero'.
Outside the Portuguese cultural sphere, the South Vietnamese đồng before 1975 used a method similar to the cifrão to separate values of đồng from its decimal subunit xu. For example, 750 meant 7 đồng and 50 xu.
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.
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. 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.) The two-stroke version seems to be generally less popular today, though used in some "old-style" fonts like Baskerville.
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.
The dollar sign "$" has Unicode code point U+0024 (inherited from ASCII via Latin-1).
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.
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, 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", though it has been requested formally.
Among others, the following fonts display a double-bar dollar sign for code point 0024: regular-weight Baskerville, Big Caslon, Bodoni MT, Garamond: ($)
In LaTeX, with the textcomp package installed, the cifrão () can be input using the command \textdollaroldstyle. However, because of font substitution and the lack of a dedicated code point, the author of an electronic document who uses one of these fonts intending to represent a cifrão cannot be sure that every reader will see a double-bar glyph rather than the single barred version. Because of the continued lack of support in Unicode, a single bar dollar sign is frequently employed in its place even for official purposes. Where there is any risk of misunderstanding, the ISO 4217 three-letter acronym is used.
The symbol is sometimes used derisively, in place of the letter S, to indicate greed or excess money such as in "Micro$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.
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.
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.
In the 1993 version of the Turkmen Latin alphabet $ was used as a transliteration of the Cyrillic letter Ш, in 1999 was replaced by the letter Ş.