Explanation

You can use the euro in 20 EU countries:

1. Austria,
2. Belgium,
3. Croatia,
4. Cyprus,
5. Estonia,
6. Finland,
7. France,
8. Germany,
9. Greece,
10. Ireland,
11. Italy,
12. Latvia,
13. Lithuania,
14. Luxembourg,
15. Malta,
16. the Netherlands,
17. Portugal,
18. Slovakia,
19. Slovenia
20. Spain.

Euro was introduced on 1 January 199

For the first 3 years, it was an invisible century

The euro is the second-largest reserve currency 

The euro is the second-most traded currency in the world