Six countries outside the EU use the euro as their only currency
The euro is not confined to the European Union. Six countries outside it use the euro as their sole official currency, in two different ways. Four small states have formal monetary agreements with the EU, which let them use the euro and mint a limited number of their own euro coins. Two others adopted the euro on their own, with no agreement and no right to mint coins. One of these two is a state whose independence is not recognised by every other country. Territories that belong to an EU member state, such as French Guiana, are not counted, because they are not countries.
Name them all first. Then sort them by whether they use the euro by agreement or on their own.