European Monetary Union
European Monetary Union (EMU) was the successor to the European Monetary System (EMS). The principal goal of the EMU was to establish a single European currency called the Euro, which would officially replace the national currencies of the member EU countries in 2002. On January 1, 1999 the transitional phase to introduce the Euro began. This transition period would last for three years, at which time Euro notes an coins would enter circulation. On July 1,2002, only Euros would be legal tender for EMU participants, and the national currencies of the member countries will cease to exist.
This has been completed by all initial EU members except for the United Kingdom and Denmark, who have opted out of adopting the euro.