No, the entire European Union does not use the euro. Of the 27 EU member states, 20 use the euro as their sole currency. These countries are collectively called the “eurozone.” Nonparticipating member states negotiated currency “opt-outs” upon their entry into the EU. For example, prior to officially leaving the EU in 2020, the United Kingdom’s opt-out agreement allowed the nation to continue using the pound sterling (£).
