The United States dollar (sign: $; code: USD) is the unit of currency of the United States The U.S. dollar is normally abbreviated as the dollar sign, $, or as USD or US$ to distinguish it from other dollar-denominated currencies and from others that use the $ symbol. It is divided into 100 cents (200 half-cents prior to 1857).
The U.S. dollar is the currency most used in international transactions.Although U.S. dollar is a fiat currency, several countries use it as their official currency, and in many others it is the de facto currency.

Overview
The U.S. dollar bill uses the decimal system, consisting of 100 equal cents (symbol ¢). In another division, there are 1,000 mills or ten dimes to a dollar, or 4 quarters to a dollar. However, only cents are in everyday use as divisions of the dollar; "dime" is used solely as the name of the coin with the value of 10¢, while "eagle" and "mill" are largely unknown to the general public, though mills are sometimes used in matters of tax levies and gasoline prices. When currently issued in circulating form, denominations equal to or less than a dollar are emitted as U.S. coins while denominations equal to or greater than a dollar are emitted as Federal Reserve notes (with the exception of gold, silver and platinum coins valued up to $100 as legal tender, but worth far more as bullion). Both one-dollar coins and notes are produced today, although the note form is significantly more common. In the past, "paper money" was occasionally issued in denominations less than a dollar (fractional currency) and gold coins were issued for circulation up to the value of $20 (known as the "double eagle," discontinued in the 1930s). The term eagle was used in the Coinage Act of 1792 for the denomination of ten dollars, and subsequently was used in naming gold coins. In 1854, James Guthrie, then Secretary of the Treasury, proposed creating $100, $50 and $25 gold coins, which were referred to as a "Union," "Half Union," and "Quarter Union," thus implying a denomination of 1 Union = $100.
Today, USD notes are made from cotton fiber paper, unlike most common paper, which is made of wood fiber.

U.S. coins are produced by the United States Mint. U.S. dollar banknotes are printed by the Bureau of Engraving and Printing, and, since 1914, have been issued by the Federal Reserve. The "large-sized notes" issued before 1928 measured 7.42 inches (188 mm) by 3.125 inches (79.4 mm); small-sized notes, introduced that year, measure 6.14 inches (156 mm) by 2.61 inches (66 mm) by 0.0043 inches (0.11 mm).

Etymology
The name Thaler (from German thal, or nowadays usually Tal, "valley", cognate with "dale" in English) came from the German coin Guldengroschen ("great guilder", being of silver but equal in value to a gold guilder), minted from the silver from a rich mine at Joachimsthal (St. Joachim's Valley, now Jáchymov) in Bohemia (then part of the Holy Roman Empire, now part of the Czech Republic).

The colloquialism buck (much like the British term "quid") is often used to refer to dollars of various nations, including the U.S. dollar. This term, dating to the 18th century, may have originated with the colonial fur trade. Greenback is another nickname originally applied specifically to the 19th century Demand Note dollars created by Abraham Lincoln to finance the costs of the Civil War for the North. The original note was printed in black and green on the back side. It is still used to refer to the U.S. dollar (but not to the dollars of other countries), other well known names of the dollar as a whole in denominations include "greenmail", "green", and "Dead Presidents", (the last one due to the nature of late presidents being the most represented on the bills).
Grand, sometimes shortened to simply G, is a common term for the amount of $1,000. The suffix k (from "kilo-") is also commonly used to denote this amount (such as "$10k" to mean $10,000). In street slang, when someone refers to a denomination "large", they are usually referring to any amount of $10,000, such as "fifty large", meaning $50,000. Banknotes' nicknames are the same as their values (such as five, twenty, etc.) The $5 bill has been referred to as a "fin" or a "fiver" or a "five-spot;" the $10 bill as a "sawbuck," a "ten-spot," or a "Hamilton"; the $20 bill as a "double sawbuck," or a "Jackson"; the $1 bill is sometimes called a "single," or a "buck," the $2 bill a "deuce," "Jefferson," or a "T.J." and the $100 bill is nicknamed a "Benjamin," "Benji," or "Franklin" (after Benjamin Franklin, who is pictured on the note), C-note (C being the Roman numeral for 100), Century Note, or "bill" ("two bills" being $200, etc.). The dollar has also been referred to as a "bone" or "bones" (i.e. twenty bones is equal to $20) or a "bean". Occasionally these will be referred to as "dead presidents," although neither Hamilton ($10) nor Franklin ($100) was President. $1000 notes are occasionally referred to as 'large' in banking ("twenty large" being $20,000, etc.). The newer designs are sometimes referred to as "Bigface" bills, or "Monopoly Money".
In Panama, the translation of buck is palo (lit. stick); a nickname for the balboa. For example: "Esto vale 20 palos" ("This is worth 20 bucks"). In Puerto Rico (as well as by Puerto Ricans living in the continental U.S.), the dollar may be referred to as a peso. In French-speaking areas of Louisiana, the dollar is referred to as a piastre which is pronounced "pee-as", and cents by the French holdhover of sous, pronounced "soo." In Mexico, prices in dollars are referred in some places to as "en americano" ("in American"): one would ask "¿Cuánto cuesta en americano?" ("How much does it cost 'in American'?") and would receive the U.S. dollar price in the Spanish language. (In Mexico, peso is used primarily for the Mexican peso.) In Peru, a nickname for the U.S. dollar is coco, which is a pet name for Jorge (George in Spanish), a reference to the portrait of George Washington on the $1 note.