The euro was introduced as book money in 1999. Since 1 January 2002, euro banknotes and coins have been legal tender in the 12 countries of the euro area, namely, Austria, Belgium, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, Netherlands, Portugal and Spain. On 1 January 2007 Slovenia became the thirteenth country to join the euro area.

European integration is based on a number of treaties which have been concluded between the States concerned since the establishment of the European Coal and Steel Community. These treaties together comprise more than 700 articles.

On 1 May 2004 the biggest round of enlargement to date took place. With the accession of 10 new Member States – Cyprus, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia – the total number of Member States rose from 15 to 25. The accession of Bulgaria and Romania on 1 January 2007 brought this number to 27.

The internal market is an area without internal frontiers in which the free movement of goods, persons, services and capital is ensured. With a population of 457 million, the European Union is the largest internal market in the world today.