The peso (sign: $; code: MXN) is the currency of Mexico. The symbol used for the peso is "$", basically the same as for the US dollar since the dollar derived its logo from the Spanish-Mexican currency. It is one of the top most traded currencies in the world . The current ISO 4217 code for the peso is MXN; prior to the 1993 revaluation (see below), the code MXP was used. The peso is subdivided into 100 centavos, represented by "¢". The name was originally used in reference to pesos oro (gold weights) or pesos plata (silver weights). The translation of peso from Spanish to English is weight. As of January 2009 its exchange rate was 14.19 Mexican pesos against one U.S. dollar.

Throughout most of the 20th century, the Mexican peso remained one of the most stable currencies in Latin America, since the economy did not experience periods of hyperinflation common to other countries in the region. However, after the Oil Crisis of the late 1970s, Mexico defaulted on its external debt in 1982 and experienced several years of inflation and devaluation until a government economic strategy called the "Stability and Economic Growth Pact" (Pacto de estabilidad y crecimiento económico, PECE) was adopted under President Carlos Salinas. On 1 January 1993, the Bank of Mexico introduced a new currency, the nuevo peso ("new peso", or MXN), written "N$" followed by the numerical amount. One new peso, or N$1.00, was equal to 1000 of the obsolete MXP pesos.

On January 1, 1996, the modifier nuevo was dropped from the name and new coins and banknotes – identical in every respect to the 1993 issue, with the exception of the now absent word "nuevo" – were put into circulation. The ISO 4217 code, however, remained unchanged as MXN.

Thanks to the stability of the Mexican economy and the growth in foreign investment, the Mexican peso is now among the 15 most traded currency units in the world, and is the most traded currency in Latin America. It has been fairly stable for the last few years; since the late 1990s the peso has traded at about $9 to $13 to the U.S. dollar.

In 2003 the Bank of Mexico began the gradual launch of a new series of bimetallic $100 coins. These number 32 – one for each of the nation's 31 states, plus the Federal District. While the obverse of these coins bears the traditional Coat of arms of Mexico, their reverses show the individual coats of arms of the component states. The first states to be celebrated in this fashion were Zacatecas, Yucatán, Veracruz, and Tlaxcala. In circulation they are extraordinarily rare, but their novelty value offsets the unease most users feel at having such a large amount of money in a single coin. Although the Bank has tried to encourage users to collect full sets of these coins, issuing special display folders for the purpose, the high cost involved has worked against them. Bullion versions of these coins are also available, with the outer ring made of gold, instead of an aluminium bronze.

The coins commonly encountered in circulation have face values of 20¢, 50¢, $1, $2, $5, $10, and $20. The $50, 10¢ and 5¢ coins are rarely seen and largely disliked by users. As of late 2006 and early 2007, the usage of 20¢ coins is also gradually declining. Small commodities are priced in multiples of 10¢, but stores may choose to round the total prices to 50¢. There is also a trend for supermarkets to ask customers to donate those cents to charities so that they can round the amount to 50¢ or 1 peso.

Starting from 2001, each denomination in the series was upgraded gradually. On October 15, 2001, in an effort to combat counterfeiting, Series D notes of 50 pesos and above were further modified with the addition of an iridescent strip. On notes of 100 pesos and above, the denomination is printed in color-shifting ink in the top right corner. On September 30, 2002 a new $20 note was introduced. The new $20 is printed on longer-lasting polymer plastic rather than paper. A new $1000 note was issued on November 15, 2004. The Bank of Mexico refers to the $20, $50, and $1000 notes during this wave of change as "series D1".

On April 5, 2004 the Chamber of Deputies approved a measure to demand that the Banco de México produce by January 1, 2006 notes and coins that are identifiable by the blind population (estimated at more than 750,000 visually impaired citizens, including 250,000 that are completely blind).

On December 19, 2005, $100, $200, and $500 MXN banknotes include raised, tactile patterns (like Braille), meant to make them distinguishable for people with vision incapacities. This system has been questioned and many demand that it be replaced by actual Braille so it can be used by foreigners not used to these symbols. The Banco de México, however, says they will continue issuing the symbol bills.

In September 2006, it was announced that a new family of banknotes will be launched gradually. The 50-peso denomination in polymer was launched in November 2006. The 20-peso note was launched in August 2007. The 1000-peso note was launched in March 2008.

The $200 was launched in 2008, and the $100 and $500 notes will be launched in 2009. This family is the F Series.

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).