cur·ren·cy

Origin: currentia 'flowing', from Latin currere; current

A currency in the most specific sense is money in any form when in use or circulation as a medium of exchange, especially circulating banknotes and coins. A more general definition is that a currency is a system of money (monetary units) in common use, especially for people in a nation. Under this definition, U.S. dollars (US$), euros (€), Japanese yen (¥), and pounds sterling (£) are examples of currencies. These various currencies are recognized as stores of value and are traded between nations in foreign exchange markets, which determine the relative values of the different currencies. Currencies in this sense are defined by governments, and each type has limited boundaries of acceptance.

Other definitions of the term "currency" appear in the respective synonymous articles: banknote, coin, and money. This article uses the definition which focuses on the currency systems of countries.

One can classify currencies into three monetary systems: fiat money, commodity money, and representative money, depending on what guarantees a currency's value (the economy at large vs. the government's physical metal reserves). Some currencies function as legal tender in certain political jurisdictions. Others simply get traded for their economic value.

Digital currency has arisen with the popularity of computers and the Internet. Whether digital notes and coins will be successfully developed remains dubious. Decentralized digital currencies, such as cryptocurrencies are not legal currency, strictly speaking, since they are not issued by a government monetary authority and are not legal tender. Many warnings issued by various countries note the opportunities that cryptocurrencies create for illegal activities, such as money laundering and terrorism. In 2014 the United States IRS issued a statement explaining that virtual currency is treated as property for Federal income-tax purposes and providing examples of how longstanding tax principles applicable to transactions involving property apply to virtual currency.

• launder [from French lavandier, from Latin lavare]: 洗熨 →laundry, lavatory, lavender

Originally money was a form of receipt, representing grain stored in temple granaries in Sumer in ancient Mesopotamia and in Ancient Egypt.

In Africa, many forms of value store have been used, including beads, ingots, ivory, various forms of weapons, livestock, the manilla currency, and ochre and other earth oxides. The manilla rings of West Africa were one of the currencies used from the 15th century onwards to sell slaves. African currency is still notable for its variety, and in many places, various forms of barter still apply.

Manillas are a form of money, usually made of bronze or copper, which were used in West Africa.

In premodern China, the need for credit and for a medium of exchange that was less physically cumbersome than large numbers of copper coins led to the introduction of paper money, i.e. banknotes. Their introduction was a gradual process that lasted from the late Tang dynasty (618–907) into the Song dynasty (960–1279). It began as a means for merchants to exchange heavy coinage for receipts of deposit issued as promissory notes by wholesalers' shops. These notes were valid for temporary use in a small regional territory. In the 10th century, the Song dynasty government began to circulate these notes amongst the traders in its monopolized salt industry. The Song government granted several shops the right to issue banknotes, and in the early 12th century the government finally took over these shops to produce state-issued currency. Yet the banknotes issued were still only locally and temporarily valid: it was not until the mid 13th century that a standard and uniform government issue of paper money became an acceptable nationwide currency. The already widespread methods of woodblock printing and then Bi Sheng's movable type printing by the 11th century were the impetus for the mass production of paper money in premodern China.

A currency-counting machine is a machine that counts money—either stacks of banknotes or loose collections of coins. Counters may be purely mechanical or use electronic components. The machines typically provide a total count of all money, or count off specific batch sizes for wrapping and storage. Currency counters are commonly used in vending machines to determine what amount of money has been deposited by customers.

六级/考研单词: medium, circulate, banknote, euro, respective, synonym, classify, commodity, physics, illicit, tender, jurisdiction, digit, compute, dubious, strict, issue, terror, unite, laundry, lavatory, grain, temple, bead, ivory, livestock, oxide, onward, slave, notable, bronze, copper, gradual, dynasty, merchant, deposit, wholesale, valid, territory, nationwide, impetus, stack, electron, component, batch, wrap