The European Union (EU) is an international organization and a unique political and economic union of 27 European countries. It is a sui generis entity that combines characteristics of a federation and a confederation, built on the concept of shared sovereignty. Its foundation is the single market, which guarantees the free movement of goods, capital, services, and people across member states.
The EU's origin lies in the post-World War II effort to secure lasting peace and make war "materially impossible" by integrating European economies. The process began with the European Coal and Steel Community (ECSC), established in 1951 by six founding countries. The EU was formally created by the Maastricht Treaty, which was signed in 1992 and entered into force on November 1, 1993, converting the earlier European Economic Community (EEC) into the Union. This treaty also introduced the euro currency and the concept of EU citizenship.
The EU functions through an "institutional triangle" that produces laws based on treaties like the Treaty on European Union. The European Commission proposes legislation, which is jointly enacted by the European Parliament (directly elected by citizens) and the Council of the European Union (representing member governments). The European Court of Justice ensures the uniform application of EU law.
Related concepts include the Eurozone, the 20 member states that use the euro, and the Schengen Area, which has abolished passport controls for travel. The EU's structure was significantly updated by the Treaty of Lisbon, which came into force in December 2009. A major recent change was the departure of the United Kingdom in 2020. Recent amendments include a landmark reform of the EU Customs Union agreed in March 2026, which will introduce a temporary €3 customs duty on low-value parcels from July 1, 2026.