Six years later they decided to go further, removing trade barriers to create a "common market", the European Economic Community. Three countries, including the UK, joined in 1973, one in 1981 and two in 1986. East Germany entered in 1990, when Germany was reunited.
The EEC became the European Union in 1992, set on a course of economic and monetary union. Three more countries joined in 1995. Twelve of the members switched to the common currency, the euro, in 2002.
On May 1, 2004, the family will increase from 15 to 25 members. A further five countries have applied to join.