Eurozone

The eurozone ( pronunciation (help info)), 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 monetary authority of the eurozone is the Eurosystem. The other nine members of the European Union continue to use their own national currencies, although most of them are obliged to adopt the euro in the future.

Question: do all countries in eu use the euro
Answer: no