A currency code is the 3-letter code, established by the ISO (International Organization for Standardization), that describes the common currency used in a specific country. These currency codes were developed in 1973 to be used in application of trade, commerce, and banking. In 1978, the UN/ECE Group of Experts officially permitted the use of 3-letter currency codes suitable in international trade.

Major Currency Codes from Wikipedia

The first 2 letters usually stand for the country name and the third letter is the initial to the country’s currency name. Examples:

• Japan and Yen – JP and Y = JPY (Japanese Yen)
• United States and Dollar – US and D = USD (United States Dollar)

Sometimes, the third letter stands for the new currency. Example:

• Mexico and Peso – MX and P = MXN (‘N’ stands for ‘new’)

Another example:

• Russia and Ruble – RU and R = RUB (‘B’ is the 3rd letter in ‘ruble’)

Precious metals currency codes (gold, silver, palladium, and platinum) – always start with ‘X’ followed by metal’s chemical symbol. Example:

• X and AG (silver’s chemical symbol) = XAG silver code

Special Drawing Rights currency code used in international finance – SRD

Special Code for Testing Purposes – XTS

No Currency Transaction code – XXX

Supranational currencies are represented by codes starting with ‘X’:

• East Caribbean dollar
• CFP franc
• CFA franc BEAC
• CFA franc BCEAO

Euro, coded EUR, represent the European Union. Former codes: ECU (European Currency Unit) and XEU.

Changes and discontinuation of use of currency are often caused by the following:

• new governments created by war and creating new constitutions
• new treaties between countries about a curreny standardization
• currency revualtion caused by inflation

More Forex Terms:

• Currency – is any form of money that a government endorses and uses for trade.
• Supranational Currency - A currency created through a decision voted by multi-national political communities, where power was transferred to an authority by governments of member states.
  
• Exotic Currency – refers to a currency that is not popularly traded.
• Currency Basket – refers to various weightings of other currencies grouped together in relation to a basket currency. Sometimes used by currencies to fix their rate, often on a trade-weighted basket.
• Currency pair – Two currencies that are used to make a trade. Examples: USD/JPY, USD/EUR,GBP/JPY, and so on.
  
• Currency risk – is known as the chance involved in exchange rates that may have negative effects.
• Base currency – is the first currency in a currency pair.
• Quote currency – is the second currency in a currency pair.

Popular Nicknames for Major Currencies:

• Greenbuck / Buck - Slang for the United States Dollar (USD).
• Fiber - Slang for Euro, the official currency of the European Union (EUR).
• Sterling – Slang for the British Pound (GBP).
• Swissy – Slang for the Swiss Franc (CHF).
• Aussie – Slang for the Australian Dollar (AUD).
• Loonie - Slang for the Canadian Dollar (CAD).
• Kiwi – Slang for the New Zealand Dollar (NZD).

Common Nicknames for Currency Pairs:

• Cable – GBP/USD
• Fiber – EUR/USD
• Chunnel – EUR/GBP
• Loonie / The Funds – USD/CAD
• Matie / Aussie – AUD/USD
• Geppie / Beast – GBP/JPY
• Kiwi – NZD/USD

Here’s a List of Currency Codes:

Sources: BabyPips.com / Wikipedia