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.
The euro is back in fashion again. External factors are mostly behind the euro's gains. It corresponds to a dollar weakness, related to President Trump's failures to get much of his agenda into law. Confidence in US policies is dwindling, and currency investors are migrating to the euro once again.