The European Union, as we know it, began with the Treaty of Rome that was signed on 27 March 1957 by the heads of state of France, Germany, Italy, The Netherlands, Belgium and Luxembourg.
In creating the European Community, as it was first called, the signatories included among their objectives:
Since then the European Union has grown and now consists of 27 member states, including since 2004 countries that were formerly part of the central and eastern European communist bloc. The UK became a member in 1973.
Click here to see how the EU has grown since 1951
The number of stars on the EU flag has nothing to do with the number of Member States.
There are twelve stars because the number twelve is traditionally the symbol of perfection, completeness and unity. However many states join, the EU the flag remains unchanged.
How the EU makes laws