The Euro is the official currency of the European Union and is used by 19 of the 28 member states. It is the second most actively traded currency in the world and is a major reserve currency. In terms of investing and financial markets, the Euro is used to facilitate international transactions and investments by allowing investors to hedge against currency fluctuations. It is also used as a benchmark for setting interest rates and can be used to invest in countries and companies within the European Union. The Euro is a popular currency for investors looking to diversify their portfolios and gain exposure to European markets.