European Currency Unit opportunity for foreign diversification without reliance on the currency of a single country. The ECU was conceived on 13 March 1979 as an internal accounting unit. It had the ISO 4217 currency code XEU. On 1 January 1999, the euro (with the code EUR and symbol €) replaced the ECU, at the value €1 = 1 ECU. Unlike the ECU, the euro is a real currency, although not all member states participate (for details on euro membership see Eurozone). Two of the countries in the ECU basket of currencies, UK and Denmark, did not join the eurozone, and a third,
International status and usage of the euro those in the eurozone, do not participate in the European Central Bank or the Euro Group. Its international usage has also grown as a trading currency, acting as an economic or political alternative to using the United States dollar. Its increasing usage in this sense has led to its becoming the only significant challenger to the US dollar as the world's main reserve currency. Several European microstates outside the EU have adopted the euro as their currency. For EU sanctioning of this adoption, a monetary agreement must be concluded. Prior to the launch of the euro, agreements were reached with