The Euro is the single currency across the 19 countries that make up the European Union (EU). It is the second most traded currency in the world, behind the US Dollar. The purpose of the Euro is to simplify transactions and investments within the EU, as well as with other countries. It reduces the need for conversion between currencies when making transactions, and provides a unified currency for trading on the financial markets. The Euro has also helped to increase the stability of the financial markets, by providing a more unified currency for investors to use. This in turn has led to increased investment in the EU, which has been beneficial for both the economy and the financial markets.