The euro is the official currency for 19 of the 27 EU member countries. A long preparatory path of over 40 years led to the introduction of the euro in 2002. The European Central Bank and the European Commission are in charge of maintaining its value and stability, and for establishing the criteria required for EU countries to enter the euro area.
Tangible proof of European integration, the single currency has a specific history of design, implementation, and policies. Although the switch to the euro took place almost 20 years ago, in some countries it is still possible to exchange old national notes and coins with the single European currency.