From 6 to 28 members
The EU is a unique economic and political partnership between 28 European countries that together cover much of the continent.
It was created in the aftermath of the Second World War. The first steps were to foster economic cooperation: the idea being that countries who trade with one another become economically interdependent and so more likely to avoid conflict.
In 1951, six countries founded the European Coal and Steel Community, and later, in 1957, the European Economic Community and the European Atomic Energy Community:
- the Netherlands
A further 22 countries have since joined the EU, including a historic expansion in 2004 marking the re-unification of Europe after decades of division:
After Slovenia, Croatia is the second country from ex-Yugoslavia to join the EU. The European perspective remains open to the entire Western Balkans region.
Two more countries from eastern Europe, Bulgaria and Romania, join the EU, bringing the number of member states to 27 countries.
Ten new countries join the EU: Czech Republic, Estonia, Cyprus, Latvia, Lithuania, Hungary, Malta, Poland, Slovakia and Slovenia. This was the largest single enlargement in terms of people, and number of countries.
Austria, Finland and Sweden join the EU. The 15 members now cover almost the whole of western Europe.
Spain and Portugal become members
Membership of the EU reaches double figures when Greece joins. It has been eligible to join since its military regime was overthrown and democracy restored in 1974.
Denmark, Ireland and the United Kingdom join the European Union, raising the number of member states to nine.
The organisation founded in 1957 which is now known as the European Union, originally had six members: Belgium, France, Germany, Italy, Luxembourg and the Netherlands.