The European Union (EU) is a unique political and economic union of 27 member states, often described as a sui generis entity combining characteristics of a federation and a confederation. Its origin lies in the desire to end the frequent and bloody conflicts in Europe, particularly the rivalry between France and Germany, which culminated in the Second World War. The first step was the European Coal and Steel Community (ECSC), established in 1951 by six founding countries (Belgium, France, Italy, Luxembourg, the Netherlands, and West Germany) to place their coal and steel industries under a common management, making war "materially impossible". The EU itself was formally created by the Maastricht Treaty (officially the Treaty on European Union), which entered into force on November 1, 1993. This treaty was designed to enhance political and economic integration by creating a single currency, the euro, a unified foreign and security policy, and common citizenship rights.
The EU's core mechanism is the internal single market, which ensures the free movement of goods, services, capital, and people across member states. The legislative function is primarily shared by three institutions: the European Parliament, which is the only directly elected body; the Council of the European Union (representing national governments); and the European Commission, which proposes legislation and acts as the executive body. The Court of Justice of the European Union (CJEU) ensures that EU law is observed and has established the doctrines of "direct effect" and "supremacy" of EU law over national law in cases of conflict. Related concepts an informed reader should know include the Eurozone, the group of EU member states that use the euro, and the Schengen Area, a zone where passport controls have been abolished for travel between participating countries. A major recent change was the withdrawal of the United Kingdom from the organization in 2020, commonly known as Brexit. The EU continues to evolve, with recent amendments including the implementation of the Entry/Exit System (EES) starting October 12, 2025, a new digital border system for the Schengen Area.