The European Union (EU) is a political and economic community of twenty-seven member states, located primarily in Europe. It was created in 1993 by the Treaty of Maastricht, adding new areas of policy to the existing European Community

The EU establishes a single market created by a system of laws which apply in all member states, guaranteeing the freedom of movement of people, goods, services and capital. It maintains a common trade policy, agricultural and fisheries policies, and a regional development policy. In 1999 it introduced a common currency, the euro, which has been adopted by fifteen member states. It has developed a role in foreign policy, representing its members in the World Trade Organization (WTO), at G8 summits and at the United Nations (UN). Twenty-one EU countries are members of NATO. It has developed a role in justice and home affairs, including the abolition of passport control between many member states under the Schengen Agreement.

Much of the EU's functioning depends upon agreement between the member states, an intergovernmental feature common to most international organisations. However, it also has supranational bodies, able to make decisions without the agreement of member states. Important institutions and bodies of the EU include the European Commission, the European Parliament, the Council of the European Union, the European Council, the European Court of Justice and the European Central Bank. EU citizens elect the Parliament every five years.

The EU traces its origins to the European Coal and Steel Community formed among six countries in 1951 and the Treaty of Rome in 1957. Since then the EU has grown in size through the accession of new member states and has increased its powers by the addition of new policy areas to its remit. The Treaty of Lisbon signed in December 2007 is intended to amend the existing treaties to update the political and legal structure of the union, if ratification is completed in 2008. The EU countries have almost 500 million citizens generating an estimated 31% share of the world's nominal gross domestic product (GDP) (US$16.6 trillion) in 2007.