The European Union (EU) is a supranational political and economic union of 27 member states that are located primarily in Europe. The Union has a total area of 4,233,255 km2 (1,634,469 sq mi) and an estimated total population of over 449 million. The EU has often been described as a sui generis political entity combining the characteristics of both a federation and a confederation.
Containing 5.8% of the world population in 2020, EU member states generated a nominal gross domestic product (GDP) of around US$16.6 trillion in 2022, constituting approximately one sixth of global nominal GDP. Additionally, all EU states except Bulgaria have a very high Human Development Index according to the United Nations Development Programme. 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 20 EU member states that have fully implemented the 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. Due to its global influence, the European Union has been described by some scholars as an emerging superpower.
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 2012, the EU was awarded the Nobel Peace Prize. The United Kingdom became the only member state to leave the EU, in 2020; ten countries are aspiring or negotiating to join it.