The euro is the single currency of the 18 EU member states that form the Euro Area. The euro has replaced the former national currencies, e.g. the Finnish mark, the D-mark and the French franc. The single currency was introduced on 1 January 1999 (2001 in Greece, 2007 in Slovenia, 2008 in Cyprus and Malta, 2009 in Slovakia, in 2011 in Estonia, and in 2014 in Latvia but existed in the period 1999-2001 only as electronic money. On 1 January 2002 euro banknotes and coins were put into circulation.
The 18 euro area member states have a single currency, a common interest rate and a common central bank.
Denmark has not introduced the euro, but the Danish krone is pegged closely to the euro in ERM II, the EU's exchange rate mechanism.