There are three communities, which together constitute the supra-national European Communities. They are:
The institutions of the three communities were merged by a Merger Treaty in 1967, though the communities themselves remained legally distinct.
In 1973 was EEC was first abridged to EC. Replacing the term European Economic Community (EEC), the name European Community was given a legal base in the Treaty of Maastricht 1992, which also established the European Union by linking the supra-national areas of the communities with the inter-governmental areas of Foreign and Security Policy and Justice and Home Affairs.
Notes
The European Community is now commonly called the EU, European Union, although the European Community still legally exists. It is the EC that has a legal personality that allows it to enter into agreements with other countries.The future
The EU Constitution proposes to merge the Community and the European Union into one single political organisation, the Union, covering all areas of co-operation and giving the EU a full legal personality. Having legal personality will allow the EU can enter into agreements with other legal entities within all areas in which the EU is 'competent'.