The eurozone officially called the euro area), is a monetary union of 19 of the 28 European Union (EU) member states which have adopted the euro (€) as their common currency and sole legal tender. The other 9 members of the European Union continue to use their own national currencies.
The eurozone consists of Austria, Belgium, Cyprus, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Portugal, Slovakia, Slovenia, and Spain. Other EU states (except for Denmark and the United Kingdom) are obliged to join once they meet the criteria to do so. No state has left, and there are no provisions to do so or to be expelled.
Andorra, Monaco, San Marino, and Vatican City have formal agreements with the EU to use the euro as their official currency and issue their own coins.
Kosovo and Montenegro have adopted the euro unilaterally, but these countries do not officially form part of the eurozone and do not have representation in the European Central Bank (ECB) or in the Eurogroup.