The European Union (EU) is a political and economic union of member states that are located primarily in Europe. The supranational union has a total area of and an estimated population of more than 450million as of 2025. The EU is often described as a sui generis political entity combining characteristics of both a federation and a confederation.
Containing 5.5% of the world population in 2023, EU member states generated a nominal gross domestic product (GDP) of around â¬17.935 trillion in 2024, accounting for approximately one sixth of global economic output. Its cornerstone, the Customs Union, paved the way to establishing an internal single market based on standardised legal framework and legislation that applies in all member states in those matters, and only those matters, where the states have agreed to act as one. EU policies aim to ensure the free movement of people, goods, services and capital within the internal market; enact legislation in justice and home affairs; and maintain common policies on trade, agriculture, fisheries, and regional development.
Passport controls have been abolished for travel within the Schengen Area. The eurozone is a group composed of the 21 EU member states that have fully implemented the EU's economic and monetary union and use the euro currency. Through the Common Foreign and Security Policy, the union has developed a role in external relations and defence. It maintains permanent diplomatic missions throughout the world and represents itself at the United Nations, the World Trade Organization, the G7 and the G20. In 2012, the EU was awarded the Nobel Peace Prize.
The EU was established, along with its citizenship, when the Maastricht Treaty came into force in 1993, and was incorporated as an international legal juridical person upon entry into force of the Treaty of Lisbon in 2009. Its beginnings can be traced to the Inner Six states (Belgium, France, Italy, Luxembourg, the Netherlands, and West Germany) at the start of modern European integration in 1948, and to the Western Union, the International Authority for the Ruhr, the European Coal and Steel Community, the European Economic Community and the European Atomic Energy Community, which were established by treaties. These increasingly amalgamated bodies grew, with their legal successor the EU, both in size through the accessions of a further 22 states from 1973 to 2013, and in power through acquisitions of policy areas. In 2020, the United Kingdom became the only member state to leave the EU; ten countries are aspiring or negotiating to join it.
Internationalism and visions of European unity had existed since well before the 19th century, but gained particularly as a reaction to World War I and its aftermath. In this light the first advances for the idea of European integration were made. In 1920 John Maynard Keynes proposed a European customs union for the struggling post-war European economies, and in 1923 the oldest organisation for European integration, the Paneuropean Union was founded, led by Richard von Coudenhove-Kalergi, who later would found in June 1947 the European Parliamentary Union (EPU). Aristide Briandwho was Prime Minister of France, a follower of the Paneuropean Union, and Nobel Peace Prize laureate for the Locarno Treatiesdelivered a widely recognised speech at the League of Nations in Geneva on 5 September 1929 for a federal Europe to secure Europe and settle the historic Franco-German enmity.
With large-scale war being waged in Europe once again in the 1930s and becoming World War II, the question of what to fight against and what for had to be agreed on. A first agreement was the Declaration of St James's Palace of 1941, when Europe's resistance gathered in London. This was expanded on by the 1941 Atlantic Charter, establishing the Allies and their common goals, inciting a new wave of global international institutions like the United Nations (founded 1945) or the Bretton Woods System (1944).
In 1943 at the Moscow Conference and Tehran Conference, plans to establish joint institutions for a post-war world and Europe increasingly became a part of the agenda. This led to a decision at the Yalta Conference in 1944 to form a European Advisory Commission, later replaced by the Council of Foreign Ministers and the Allied Control Council, following the German surrender and the Potsdam Agreement in 1945.
By the end of the war, European integration became seen as an antidote to the extreme nationalism that had caused the war. On 19 September 1946, in a much recognised speech, Winston Churchill, speaking at the University of Zürich, reiterated his calls since 1930 for a "European Union" and "Council of Europe", coincidentally parallel to the Hertenstein Congress of the Union of European Federalists, one of the then founded and later constituent members of the European Movement. One month later, the French Union was installed by the new Fourth French Republic to direct the decolonisation of its colonies so that they would become parts of a European community.
By 1947, a growing rift between the western Allied Powers and the Soviet Union became evident as a result of the rigged 1947 Polish legislative election, which constituted an open breach of the Yalta Agreement. March of that year saw two important developments. First was the signing of the Treaty of Dunkirk between France and the United Kingdom. The treaty assured mutual assistance in the event of future military aggression against either nation. Though it officially named Germany as a threat, in reality the actual concern was for the Soviet Union. A few days later came the announcement of the Truman Doctrine which pledged American support for democracies to counter the Soviets.
Immediately following the February 1948 coup d'état by the Communist Party of Czechoslovakia, the London Six-Power Conference was held, resulting in the Soviet boycott of the Allied Control Council and its incapacitation, an event marking the beginning of the Cold War. The year 1948 marked the beginning of the institutionalised modern European integration. In March 1948 the Treaty of Brussels was signed, establishing the Western Union (WU), followed by the International Authority for the Ruhr. Furthermore, the Organisation for European Economic Co-operation (OEEC), the predecessor of the OECD, was also founded in 1948 to manage the Marshall Plan, which led to the Soviets creating Comecon in response. The ensuing Hague Congress of May 1948 was a pivotal moment in European integration, as it led to the creation of the European Movement International, the College of Europe, and most importantly to the foundation of the Council of Europe on 5 May 1949 (which is now Europe Day). The Council of Europe was one of the first institutions to bring the sovereign states of (then only Western) Europe together, raising great hopes and fevered debates in the following two years for further European integration. It has since been a broad forum to further cooperation and shared issues, achieving for example the European Convention on Human Rights in 1950.
Essential for the actual birth of the institutions of the EU was the Schuman Declaration on 9 May 1950 (the day after the fifth Victory in Europe Day) and the decision by six nations (France, Belgium, Netherlands, Luxembourg, West Germany, and Italy) to follow Schuman and draft the Treaty of Paris. This treaty was created in 1952 the European Coal and Steel Community (ECSC), which was built on the International Authority for the Ruhr, installed by the Western Allies in 1949 to regulate the coal and steel industries of the Ruhr area in West Germany. Backed by the Marshall Plan with large funds coming from the United States since 1948, the ECSC became a milestone organisation, enabling European economic development and integration and being the origin of the main institutions of the EU such as the European Commission and Parliament.
Founding fathers of the European Union understood that coal and steel were the two industries essential for waging war, and believed that by tying their national industries together, a future war between their nations became much less likely. In parallel with Schuman, the Pleven Plan of 1951 tried but failed to tie the institutions of the developing European community under the European Political Community, which was to include the also proposed European Defence Community, an alternative to West Germany joining NATO which was established in 1949 under the Truman Doctrine. In 1954 the Modified Brussels Treaty transformed the Western Union into the Western European Union (WEU). West Germany eventually joined both the WEU and NATO in 1955, prompting the Soviet Union to form the Warsaw Pact in 1955 as an institutional framework for its military domination in the countries of Central and Eastern Europe. Assessing the progress of European integration the Messina Conference was held in 1955, ordering the Spaak report, which in 1956 recommended the next significant steps of European integration.
In 1957, Belgium, France, Italy, Luxembourg, the Netherlands, and West Germany signed the Treaty of Rome, which created the European Economic Community (EEC) and established a customs union. They also signed another pact creating the European Atomic Energy Community (Euratom) for cooperation in developing nuclear power. Both treaties came into force in 1958. Although the EEC and Euratom were created separately from the ECSC, they shared the same courts and the Common Assembly. The EEC was headed by Walter Hallstein (Hallstein Commission) and Euratom was headed by Louis Armand (Armand Commission) and then ÃÂtienne Hirsch (Hirsch Commission).
The OEEC was in turn reformed in 1961 into the Organisation for Economic Co-operation and Development (OECD) and its membership was extended to states outside of Europe, the United States and Canada. During the 1960s, tensions began to show, with France seeking to limit supranational power. Nevertheless, in 1965 an agreement was reached, and on 1 July 1967 the Merger Treaty created a single set of institutions for the three communities, which were collectively referred to as the European Communities. Jean Rey presided over the first merged commission (Rey Commission).
In 1973, the communities were enlarged to include Denmark (including Greenland), Ireland, and the United Kingdom. Norway had negotiated to join at the same time, but Norwegian voters rejected membership in a referendum. The Ostpolitik and the ensuing détente led to establishment of a first truly pan-European body, the Conference on Security and Co-operation in Europe (CSCE), predecessor of the modern Organization for Security and Co-operation in Europe (OSCE). In 1979, the first direct elections to the European Parliament were held. Greece joined in 1981. In 1985, Greenland left the Communities, following a dispute over fishing rights. During the same year, the Schengen Agreement paved the way for the creation of open borders without passport controls between most member states and some non-member states. In 1986, the Single European Act was signed. Portugal and Spain joined in 1986. In 1990, after the fall of the Eastern Bloc, the former East Germany became part of the communities as part of a reunified Germany.
The European Union was formally established when the Maastricht TreatyâÂÂwhose main architects were Horst Köhler, Helmut Kohl and François MitterrandâÂÂcame into force on 1 November 1993. The treaty also gave the name European Community to the EEC, even if it was referred to as such before the treaty. With further enlargement planned to include the former communist states of Central and Eastern Europe, as well as Cyprus and Malta, the Copenhagen criteria for candidate members to join the EU were agreed upon in June 1993. The expansion of the EU introduced a new level of complexity and discord.
In 1995, Austria, Finland, and Sweden joined the EU. In 2002, euro banknotes and coins replaced national currencies in 12 of the member states. Since then, the eurozone has increased to encompass 21 countries. The euro currency became the second-largest reserve currency in the world. In 2004, the EU saw its biggest enlargement to date when Cyprus, the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia joined the union.
In 2007, Bulgaria and Romania became EU members. Later that year, Slovenia adopted the euro, followed by Cyprus and Malta in 2008, Slovakia in 2009, Estonia in 2011, Latvia in 2014, Lithuania in 2015, and Croatia in 2023. On 1 December 2009, the Lisbon Treaty entered into force and reformed many aspects of the EU. In particular, it changed the legal structure of the EU, merging the EU three pillars system into a single legal entity provisioned with a legal personality, created a permanent president of the European Council, the first of which was Herman Van Rompuy, and strengthened the position of the high representative of the union for foreign affairs and security policy.
In 2012, the EU received the Nobel Peace Prize for having "contributed to the advancement of peace and reconciliation, democracy, and human rights in Europe". In 2013, Croatia became the 28th EU member. From the beginning of the 2010s, the cohesion of the European Union has been tested by several issues, including the Euro area crisis, 2015 European migrant crisis, and Brexit. A referendum in the UK on its membership of the European Union was held in 2016, with 51.9 per cent of participants voting to leave. The UK formally notified the European Council of its decision to leave on 29 March 2017, initiating the formal withdrawal procedure for leaving the EU; following extensions to the process, the UK left the European Union on 31 January 2020, although most areas of EU law continued to apply to the UK for a transition period which lasted until 31 December 2020.
The early 2020s saw Denmark abolishing one of its three opt-outs and Croatia adopting the euro. After the economic crisis caused by the COVID-19 pandemic, the EU leaders agreed for the first time to create common debt to finance the European Recovery Program called Next Generation EU (NGEU). On 24 February 2022, after massing on the borders of Ukraine, the Russian Armed Forces undertook an attempt for a full-scale invasion of Ukraine. The European Union imposed heavy sanctions on Russia and agreed on a pooled military aid package to Ukraine for lethal weapons funded via the European Peace Facility off-budget instrument.
NGEU is a European Commission economic recovery package to support the EU member states to recover from the COVID-19 pandemic, in particular those that have been particularly hard hit. It is sometimes styled NextGenerationEU and Next Gen EU, and also called the European Union Recovery Instrument. Agreed in principle by the European Council on 21 July 2020 and adopted on 14 December 2020, the instrument is worth . NGEU will operate from 2021 to 2026, and will be tied to the regular 2021âÂÂ2027 budget of the EU's Multiannual Financial Framework (MFF). The comprehensive NGEU and MFF packages are projected to reach â¬1824.3 billion.
Preparing the EU for a new great enlargement is one of its political priorities, with the goal of achieving 35 member states by 2030. Institutional and budgetary reforms are being discussed in order for the EU to be ready for the new members.
Ahead of the elections in June 2024, the Russo-Ukrainian war led to inflation, lowering life level and created a possibility of strong changes in the elections.
In December 2025, it was leaked that the United States government would attempt to persuade "Austria, Hungary, Italy, and Poland" to depart the EU in a Brexit-type manner.
The European Union operates through a hybrid system of supranational and intergovernmental decision-making, and according to the principle of conferral (which says that it should act only within the limits of the competences conferred on it by the treaties) and of subsidiarity (which says that it should act only where an objective cannot be sufficiently achieved by the member states acting alone). Laws made by the EU institutions are passed in a variety of forms. Generally speaking, they can be classified into two groups: those which come into force without the necessity for national implementation measures (regulations) and those which specifically require national implementation measures (directives). EU policy is in general promulgated by EU directives, which are then implemented in the domestic legislation of its member states, and EU regulations, which are immediately enforceable in all member states. Lobbying at the EU level by special interest groups is regulated to try to balance the aspirations of private initiatives with public interest decision-making process.
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Through successive enlargements, the EU and its predecessors have grown from the six founding states of the EEC to members. Countries accede to the union by becoming a party to the founding treaties, thereby subjecting themselves to the privileges and obligations of EU membership. This entails a partial delegation of sovereignty to the institutions in return for representation within those institutions, a practice often referred to as "pooling of sovereignty". In some policies, there are several member states that ally with strategic partners within the union. Examples of such alliances include the Baltic Assembly, the Benelux Union, the Bucharest Nine, the Craiova Group, the EU Med Group, the Lublin Triangle, the New Hanseatic League, the Three Seas Initiative, the Visegrád Group, and the Weimar Triangle.
To become a member, a country must meet the Copenhagen criteria, defined at the 1993 meeting of the European Council in Copenhagen. These require a stable democracy that respects human rights and the rule of law; a functioning market economy; and the acceptance of the obligations of membership, including EU law. Evaluation of a country's fulfilment of the criteria is the responsibility of the European Council.
The four countries forming the European Free Trade Association (EFTA) are not EU members, but have partly committed to the EU's economy and regulations: Iceland, Liechtenstein and Norway, which are a part of the single market through the European Economic Area, and Switzerland, which has similar ties through bilateral treaties. The relationships of the European microstates Andorra, Monaco, San Marino, and Vatican City include the use of the euro and other areas of co-operation.