The yen (?, en?) (sign: ¥; code: JPY) is the currency of Japan. It is the third most-traded currency in the foreign exchange market after the euro and the United States dollar. It is also widely used as a reserve currency after the U.S. dollar, the euro and the pound sterling. As is common when counting in East Asia, large quantities of yen are often counted in multiples of 10,000 (man, ?) in the same way as values in Western countries are often quoted in thousands.

The yen lost most of its value during and after World War II. After a period of instability, in 1949, the value of the yen was fixed at ¥360 per US$1 through a United States plan, which was part of the Bretton Woods System, to stabilize prices in the Japanese economy. That exchange rate was maintained until 1971, when the United States abandoned the gold standard, which had been a key element of the Bretton Woods System, and imposed a 10 percent surcharge on imports, setting in motion changes that eventually led to floating exchange rates in 1973.

Following the United States' measures to devalue the dollar in the summer of 1971, the Japanese government agreed to a new, fixed exchange rate as part of the Smithsonian Agreement, signed at the end of the year. This agreement set the exchange rate at ¥308 per US$1. However, the new fixed rates of the Smithsonian Agreement were difficult to maintain in the face of supply and demand pressures in the foreign-exchange market. In early 1973, the rates were abandoned, and the major nations of the world allowed their currencies to float.

Coins were introduced in 1870. There were silver 5, 10, 20 and 50 sen and 1 yen, and gold 2, 5, 10 and 20 yen. Gold 1 yen were introduced in 1871, followed by copper 1 rin, ½, 1 and 2 sen in 1873.

Cupronickel 5 sen coins were introduced in 1889. In 1897, the silver 1 yen coin was demonetized and the sizes of the gold coins were reduced by 50%, with 5, 10 and 20 yen coins issued. In 1920, cupro-nickel 10 sen coins were introduced.

Production of silver coins ceased in 1938, after which a variety of base metals were used to produce 1, 5 and 10 sen coins during the Second World War. Clay 5 and 10 sen coins were produced in 1945 but not issued for circulation.

After the war, brass 50 sen, 1 and 5 yen were introduced between 1946 and 1948. In 1949, the current type of holed 5 yen was introduced, followed by bronze 10 yen (of the type still in circulation) in 1951.

As of 29 December 2008, 500 yen coins are the highest valued coins to be used regularly in the world (this place is typically taken by the 5 Cuban convertible peso coins), with values in the neighbourhood of US$5.50, €3.90, £3.80 and CHF 5.80. The United States' largest-valued commonly-used coin (25¢) is worth ¥23; the Eurozone's largest (€2) is worth ¥255; the United Kingdom's largest (£2) is worth ¥260; and Switzerland's largest (CHF 5) is worth ¥430. Because of this high face value, the 500 yen has been a favourite target for counterfeiters. It was counterfeited to such an extent that in 2000 a new series of coins was issued with various security features. In spite of these changes, however, counterfeiting continues.

The issuance of the yen banknotes began in 1872, two years after the currency was introduced. Throughout its history, the denominations have ranged from 10 yen to 10000 yen.

Before and during World War II, various bodies issued banknotes in yen, such as the Ministry of Finance and the Imperial Japanese National Bank. The Allied forces also issued some notes shortly after the war. Since then, the Bank of Japan has been the exclusive note issuing authority. The bank has issued five series after World War II. Series E, the current series, consists of ¥1000, ¥2000, ¥5000, and ¥10,000.

The leu ([lew], plural: lei [lej]; ISO 4217 code RON; numeric code 946) is the currency of Romania. It is subdivided into 100 bani (singular: ban). On 1 July 2005, Romania underwent a currency reform, switching from the previous leu (ROL) to a new leu (RON). 1 RON is equal to 10,000 ROL.

Romania joined the European Union on 1 January 2007 and it is expected to adopt the euro in 2014.

On August 15, 1947, a revaluation took place, with a new leu replacing the old one at a rate of 20,000 old lei = 1 new leu. This revaluation, called a monetary reform or stabilisation measure (mica stabilizare, marea stabilizare), was carried out by the Communist authorities with absolutely no advance warning and without the possibility to exchange more than a fixed amount of money for the new currency. This was done in order to depose the former middle and upper classes of their last assets, after nationalization, to prepare for collectivization and to finalize the installation of communism. At the time of its introduction, 150 new lei equalled 1 U.S. dollar.

In the 1990s, after the downfall of communism, inflation ran high due to reform failures, the legalization of owning foreign currency in 1990, and the bankrupt policies of the former communist era, reaching rates as high as 300% per year in 1993. By September 2003, one euro was exchanged for more than 40,000 lei, this being its peak value. Following a number of successful monetary policies in the late 1990s and early 2000s, the situation became gradually more stable, with one digit inflation in 2005.

The Romanian leu briefly held the dubious distinction of being the world's least valued currency unit, from January (when the Turkish lira dropped six zeros) to July 2005. However, the 1,000,000 lei bill was not the highest Romanian denomination ever. This distinction belongs to the 5 million lei bill from 1947.

On 1 July 2005, the leu was revalued at the rate of 10,000 "old" lei (ROL) for one "new" leu (RON), thus psychologically bringing the purchasing power of the leu back in line with those of other major Western currencies. The term chosen for the action was "denominare", similar to the English "denomination", to signify not a conversion, but rather a total reinvention.

The first day brought difficulties adjusting to the new paper currencies and closed ATMs (that needed reprogramming) and forcing a new calculation habit that slowed down shops and annoyed some salespeople and shoppers. The old ROL currency banknotes remained in circulation until December 31, 2006 (coins remained in circulation only until December 31, 2005), but all accounts have been converted starting July 1, 2005. There is no conversion time limit between the currencies. Retailers had to display prices in both old and new currency from March 1, 2005 until June 30, 2006. The appreciation of the leu during 2005 was about 20% against a basket of major currencies.

As of 2006, the revaluation is a potential source of confusion, especially to visitors, since both old and new currency values are commonly quoted. When written, the very large amounts in old currency are usually obvious, but in speaking inhabitants might refer to an amount of 5 new lei as simply "fifty" in reference to its value 50,000 old lei.

In 1952, coins were introduced in denominations of 1, 3, 5, 10 and 25 bani, with the 1, 3 and 5 struck in aluminium bronze and the others in cupro-nickel. In 1955, cupro-nickel 50 bani were added.

In 1960, a new coinage was introduced, consisting of 15 and 25 bani, with 5 bani, 1 and 3 lei coins added in 1963. All were struck in nickel-clad steel. In 1975, aluminium replaced steel in the 5 and 15 bani, with the same change happening for the 25 bani in 1982. Aluminium 5 lei were introduced in 1978.

Following the end of the communist regime, a new coinage was introduced between 1990 and 1992, consisting of 1 leu in bronze clad steel, 5 and 10 lei in nickel plated steel, 20 and 50 lei in brass clad steel and nickel plated steel 100 lei.

As inflation took its toll, 500, 1000 and 5000 lei coins were introduced in 1999, 2000 and 2001, respectively, and were the only coins circulating when the revaluation occurred. They were all criticized for being clumsy and difficult to use. The 500 lei coins were very thick (about 0.3 cm). Despite their small value, it took only a handful of such coins to fill one's pocket. They were also made of poor material and could be occasionally found with bite marks. The 1000 lei coin was considered too small and was also cheaply made, and the 5000 lei coin was not circular (it was a dodecagon). This made it awkward to handle and difficult to use in slot machines, where it was frequently the only coin accepted. The 500, 1000 and 5000 lei coins became worth 5, 10 and 50 bani with the revaluation.

In 1952, the Ministry of Finance introduced notes for 1, 3 and 5 lei, and the Banca Republicii Populare Romane introduced 10, 25 and 100 lei notes. In 1966, the Banca Nationala a Republicii Socialiste Romania took over the production of all paper money, issuing notes for 1, 3, 5, 10, 25, 50 and 100 lei.

In 1991, 500 and 1000 lei notes were introduced, followed by 200 and 5000 lei notes in 1992, 10,000 lei in 1994, 50,000 lei in 1996, 100,000 lei in 1998, 500,000 lei in 2000 and 1 million lei in 2003. There was also a 2000 lei note, introduced in 1999; it celebrated the total solar eclipse that occurred on August 11th, 1999. The final issues of the 2000, 10,000, 50,000, 100,000, 500,000 and 1 million lei were polymer notes.

Notes in circulation at the revaluation were:

* 10,000 lei (became 1 leu)
* 50,000 lei (became 5 lei)
* 100,000 lei (became 10 lei)
* 500,000 lei (became 50 lei)
* 1,000,000 lei (became 100 lei)

In 2005, polymer notes were introduced for 1, 5, 10, 50, 100 and 500 lei. 200 lei notes were added in 2006. The designs of the 1, 5, 10, 50 and 100 lei notes are based on those of the earlier 10,000, 50,000, 100,000, 500,000 and 1 million lei notes which they replaced. The 10 lei bill was redesigned in November 2008 (most of the graphic elements are identical, some of the safety elements were withdrawn, making its safety degree similar the the lower values of 1 leu and 5 lei bills).