The European Union (EU) is a political and economic union of 27 European countries that work together on various issues such as trade, security, and human rights. Established in the aftermath of World War II to promote peace and stability in Europe, the EU has developed into a single market with a common currency, the Euro, used by 19 member states. The EU also has its own institutions, including the European Parliament, the European Commission, and the Council of the European Union, which play key roles in decision-making and policy implementation within the union.