Euro banknotes and coins were put into circulation on 1 January 2002. Today the euro is the national currency of 19 of the 28 EU member states. These 19 countries belong to the Economic and Monetary Union as a result of a European Council decision based on the fulfilment of the convergence criteria (also known as the Maastricht criteria).
These countries, which also form the eurozone, are Austria, Belgium, Cyprus, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Portugal, Slovakia, Slovenia and Spain.
The countries outside the eurozone are Bulgaria, Croatia, the Czech Republic, Denmark, Hungary, Poland, Romania, Sweden and the UK. Denmark and Lithuania belong to the Exchange Rate Mechanism II (ERM II) which means that their currencies are pegged to the euro. It is anticipated that more EU member states will join ERM II in due course.
The euro has also been adopted as legal tender by the small states of Monaco, San Marino, the Vatican City and Andorra.