Currency is the unit of money used by the people of a country or Union for buying and selling goods and services.

Certain currencies are said to be "pegged" or "fixed" to something, usually another currency. A fixed or pegged currency is one that has a constant value compared to what it is pegged to. For example, the Cape Verdian escudo is pegged to the Euro. If the value of the Euro goes up 1% compared to another form of currency, the value of the escudo also goes up 1% compared to that same currency.  

Many countries have used systems where their currency was pegged to a commodity rather than to another currency. Most used either gold or silver. When they did this, as the value of gold increased, so did the value of their money. This was called the "gold standard" or "silver standard". Most countries stopped using silver and gold standards in the 20th century. 

Some well-known currencies are:
 the United States dollar
 the Euro
 the British pound

Names of different currencies around the world
This list appears in alphabetical order:
 Afghani - Afghanistan
 Baht - Thailand
 Balboa - Panama (U.S. dollar used for paper money)
 Birr - Ethiopia
 Bolívar - Venezuela
 Boliviano - Bolivia
 Cedi - Ghana
 Colón - Costa Rica
 Cordoba - Nicaragua
 Crown - Czech Republic (koruna), Denmark (krone), Estonia (kroon), Iceland (króna), Norway (krone), Sweden (krona). See also: British Crown (coin)
 Dalasi - The Gambia
 Dinar - Algeria, Bahrain, Iraq, Jordan, Kuwait, Serbia, Tunisia 
 Denar - North Macedonia
 Dirham - Morocco, United Arab Emirates, Libya, Qatar, Jordan
 Dollar - Many countries, including the United States, Canada, Australia, New Zealand, Hong Kong, and others
 Dong - Vietnam
 Drachma - (Greece--now uses euro)
 Dram - Armenia
 Escudo - Cape Verde, (Portugal--now uses euro)
 Euro 
 European Union (as an organisation; the euro is not legal tender in every EU country.)
 EU members: Austria, Belgium, Estonia, Finland, France (except Pacific territories using CFP Franc), Germany, Greece, Ireland, Italy, Latvia, Lithuania, Luxembourg, Netherlands, Portugal, Slovakia, Spain. 
 Countries that have made legal agreements with the EU to use the euro: Andorra, Monaco, San Marino, Vatican City.
 Countries that unilaterally use the euro: Montenegro and Kosovo.
 Currencies pegged to the euro: Cape Verdian escudo, CFA franc, CFP Franc, Comoran francs, Bulgarian lev, Danish krone, the convertible marka of Bosnia and Herzegovina 
 Forint - Hungary
 Franc 
 Swiss franc - Switzerland, Liechtenstein.
 CFA franc - Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Côte d'Ivoire, Democratic Republic of the Congo, Equatorial Guinea, Gabon, Guinea, Guinea-Bissau, Republic of the Congo, 
 CFP Franc - France's Pacific territories of New Caledonia, French Polynesia, Wallis and Futuna.
 Comoran francs - Comoros (pegged to the French franc, then the euro).
 Djiboutian franc - Djibouti (pegged to the US dollar since 1973).
 Formerly using Begian-luxembourgish franc - Belgium, Luxembourg.
 Formerly using French franc: Andorra, Monaco, France (including: French Guiana, Guadeloupe, Martinique and La Réunion, Saint Pierre and Miquelon and Mayotte). 
 Gourde - Haiti
 Guilder - Aruba, Netherlands Antilles (Netherlands--now uses euro)
 Iranian real - Iran
 Kina - Papua New Guinea
 Koruna - Czech Republic (Slovakia now uses euro)
 Kroon - Estonia
 Krona - Iceland, Sweden
 Krone - Denmark, Faroe Islands, Greenland, Norway
 Kuna - Croatia
 Kwacha - Zambia and Malawi
 Kwanza - Angola
 Kyat - Burma
 Lari - Georgia
 Lats - Latvia
 Lek - Albania
 Lempira - Honduras
 Leone - Sierra Leone
 Leu - Romania, Moldova
 Lev - Bulgaria
 Lira - (Cyprus, Italy, San Marino, Vatican City--now use euro)
 Turkish lira - Turkey
 Litas - Lithuania
 Manat
 Azerbaijani manat - Azerbaijan
 Turkmen manat - Turkmenistan
 Mark - (Germany-- now uses euro)
 Marka - Bosnia and Herzegovina
 Markka - (Finland now uses euro)
 Nakfa - Eritrea
 Namibian dollars - Namibia
 Ngultrum - Bhutan
 Pataca - Macau
 Peseta - (Andorra, Spain--now use euro)
 Peso - Argentina, Chile, Colombia, Cuba, Dominican Republic (Dominican peso, Mexico, Philippines, Uruguay
 Pound - Cyprus, Egypt, Falkland Islands, Gibraltar, Guernsey, Jersey, United Kingdom (Ireland--now uses euro)
 Pula - Botswana
 Quetzal - Guatemala
 Rand - South Africa
 Real - Brazil
 Renminbi - People's Republic of China
 Riel - Cambodia
 Ringgit - Malaysia
 Riyal - Saudi Arabia
 Rouble - Belarus, Russia
 Rufiyah - Maldives
 Rupee - Republic of India, Mauritius, Nepal, Pakistan, Seychelles, Sri Lanka
 Rupiah - Indonesia
 Schilling - (Austria--now uses euro)
 Shekel - Israel, Gaza Strip, West Bank
 Shilling - Kenya
 Sol - Peru
 Som - Kyrgyzstan
 Sucre - Ecuador
 Taka - Bangladesh
 Tenge - Kazakhstan
 Tolar - Slovenia
 Toman - Iran
 Vietnam ~ Dong (DVN)
 Won - North Korea, South Korea
 Yen - Japan
 Yuan - People's Republic of China
 Zloty - Poland