How did countries give up their own money for the euro, and who runs it?

Countries gave up their own money for the euro by promising it in a treaty and then switching over in stages. Through the Maastricht Treaty of 1992 (or later accession treaties), most EU member states committed to adopt the euro once they met certain monetary and budgetary convergence criteria. Today the euro is the official currency of 21 of the EU's 27 member states, a group known as the eurozone; the 21st, Bulgaria, joined on 1 January 2026.

The switch happened in steps. The euro was introduced to financial markets as an accounting currency on 1 January 1999. Physical coins and banknotes entered circulation on 1 January 2002, and by March 2002 the old currencies had been completely replaced.

Not everyone joined. The Maastricht Treaty gave Denmark and the United Kingdom opt-outs, with the right to decide if and when to adopt the euro.

Running the euro is the job of the European Central Bank and the Eurosystem, made up of the central banks of the eurozone countries. As an independent central bank, the ECB has sole authority to set monetary policy, and its primary objective is price stability in the eurozone. In 2021 it adopted a 2% symmetric inflation target over the medium term.

Even choosing the first president was tense. France wanted a French president because the bank sat in Germany, while the German, Dutch and Belgian governments saw Wim Duisenberg as a guarantor of a strong euro. A gentleman's agreement had him stand down early, to be replaced by Jean-Claude Trichet.