The Euro is the offician currency of the EU member states of Austria, Belgium, Finland, France, Germany, Greece, Ireland, Luxembourg, the Netherlands, Portugal, and Spain (the Eurozone). It is managed and administered by the European Central Bank. It has sole authorite to set monetary policy.
All Euros have a common side showing their value with the EU countries in the background and a national side showing an image from the country that issued the coin.
The most obvious benefit of adopting a single currency is removing from trade the cost of exchanging currency, theoretically allowing businesses and individuals to consummate previously unprofitable trades. On the consumer side, banks in the Eurozone must charge the same for intra-member cross-border transactions as purely domestic transactions for electronic payments
Financial markets on the continent are expected to be more liquid and flexible than they were in the past. The reduction in cross-border transaction costs will allow larger banking firms to provide a wider array of banking services that can compete across and beyond the Eurozone.