Currently, there are 12 countries that comprise a common Euro area (monetary union), although 25 countries constitute the member states of the European Union (EU). Some of the EU member countries are actively trying to be the part of the Euro area by fulfilling the four broad convergence criteria stipulated.
The objective of monetary union in the euro area was clearly defined in the Maastricht Treaty and the primary objective of the European Central Bank (ECB) is to maintain price stability in the euro area. Price stability was then defined by the European Central Bank as an inflation rate of below but close to 2 per cent over the medium-term.