The Euro is the official currency of 19 European countries that are part of the European Union. It is used as a single currency to facilitate the trading of goods and services within the Eurozone. In terms of investing and financial markets, the Euro is used in international transactions and investments, allowing investors to purchase stocks and bonds, invest in foreign exchange, and buy and sell commodities. It is also used as the base currency for many financial products, such as derivatives and futures contracts. The Euro is an important tool in the global economy, providing stability, liquidity, and price discovery to the markets it serves.