The article explores why some countries use the euro as their currency for international trade. By analyzing a large dataset and using a panel model, the researchers found that being part of the EU makes countries more likely to use the euro for invoicing. The euro is becoming more popular as a currency for trade, but the U.S. dollar is still more widely used. Countries with unstable money and similar products tend to use the U.S. dollar for trade. However, when the euro's value is more volatile, it is more likely to be used. Additionally, countries with a strong market presence and those in the euro area are more likely to use the euro for invoicing.