(1) US Dollar - USA
This currency is among the world's most popular, universally accepted and dominant reserve currencies and is most used in international transactions. Abbreviated as US$, United States' dollar is the official currency of the United States of America. It is divided into 100 units  "Cents". The nickname of this currency. is Greenback.

(2) The Euro - Europe
This is the second most traded currency in the world. The Euro was introduced to world financial markets as an accounting currency on January 1, 1999 replacing the European Currency Unit. It is the official currency of the Euro zone (Europe) and is recognized with the symbol €.

(3) The Yen - Japan
The Japanese Yen is the official currency of Japan. It is also widely used > as a reserve currency after the US Dollar and the Euro. The government began issuing the Yen banknotes in 1872, two years after the currency was introduced. ¥ Is the currency sign of the Japanese Yen.

(4) The Pound - Britain
A common slang term for this currency is QUID. Commonly known as pound. The Pound Sterling is the official currency the United Kingdom and the crown dependencies (Dominons). The Bank of England issued the first Sterling notes shortly after it was founded in 1694. It is recognized with the symbol £. Its smaller denominations are called Pence. There is a saying also about Pound - "Penny wise Pound foolish".

This currency, started in 1694 seems to be the oldest currency of the world..

5. Australian Dollar - Australia
The currency of the Commonwealth of Australia is the Australian Dollar. It is recognized worldwide with the code AUD and its symbol is $. The first paper notes of Australian Dollar were issued in 1966 and foreign exchange traders popularly refer to this currency as the Aussie.

6. Swiss Franc - Switzerland
Swiss Franc is the official currency of Switzerland and Liechtenstein. The Swiss Bank took over the issuance of bank notes from the cantons and various banks. The Swiss franc is the only version of the franc still issued in Europe and has the symbol Fr.

7. Canadian Dollar - Canada
Canadian Dollar is the official currency of Canada. The Canadian Dollar currency is abbreviated as C$ to distinguish it from the other Dollar currencies from various countries in use. The Canadian Dollar is considered to be one of the benchmark currencies and also popularly traded across the world.

8. The Hong Kong Dollar - Hong Kong
font face="Comic Sans MS" color="#003300"> The Hong Kong Dollar is the 8th most traded currency in the world. It is respected as the official currency of Hong Kong. It is commonly identified with the code HKD or $HK. Issuance of the Hong Kong Dollar notes is governed by the Hong Kong Monetary Authority.

9. Swedish Crown - Sweden
Sweden has had Krona as its currency since 1873. As Krona means "Crown" in Swedish, The currency is commonly referred to as the Swedish Crown. The plural of the currency is Kronor and is recognized with the symbol kr internationally.

11. New Zealand Dollar - New Zealand
New Zealand dollar is the official currency of New Zealand and is normally written as NZ$ to differentiate it from other dollar denominated currencies. The currency was introduced in 1967 and is informally called the Kiwi.

12. South Korean Won - South Korea
The official currency of South Korea is the Won and has the symbol ₩. The Bank of Joseon introduced 10 and 100 Won notes in 1946. The currency is derived from a Chinese character which means round shape. The current Won is written in hangul only.

13. Singapore Dollar - Singapore
Acknowledged with the sign $ and code SGD, Singapore dollar is the official currency of Singapore and is alternatively distinguished as S$ from other dollar denominated currencies. The first series of coins were introduced in 1967.

14. Norway Krone - Norway
The Krone is  the official currency of Norway and its depending territories. The name of the currency translates to "Crown" in English and its common local abbreviation is kr. Norges Bank introduced the paper notes in 1877.

15. The Mexican Peso - Mexico
The Peso is the offcial currency of Mexico and has $ or Mex$ as its symbol. Peso when translated in English means weight. The Mexican State produced its first bank notes for this currency in 1823. Other than USA, Guatemalan and Belizean border towns, this currency is not accepted outside Mexico.

16. The Indian Rupee - India
The Indian Rupee is the official currency of India. The Reserve Bank of India monitors the issuance of this currency and the Indian Rupee is recognized with the symbol (Rs). The new Indian Rupee symbol was officially adopted in 2010. The new symbol of this currency can be entered by computer key board.

There are many more currencies in the world, like UAE's Durham, Saudi's Riyal, Pakistan's "Rupiya", Bangla Desh's "Taka", South Africa's "Rand", Lesotho's "Rand" etc etc