The euro is the official currency of the eurozone, which consists of 19 of the 28 EU member states. It is the second-largest reserve currency in the world after the US dollar.
Since 1999, the euro has been used as an accounting currency in global financial markets. Physical euro coins and banknotes entered into circulation in 2002. In 2009, the euro has become immersed in Europe's sovereign debt crisis which forced the eurozone to adopt a raft of reforms to stabilize the currency.