What Is The Definition Of The Eurozone?

The collective group of countries which use the Euro as their common currency. The Eurozone came into being in 1999, and originally consisted of 11 countries. As of 2009, 16 countries were part of the Eurozone. The Eurozone does not include every country in the European Union (some countries are not yet using the Euro), and does not include every country who is using the Euro (to become part of the Eurozone, the country must use the Euro as its sole legal currency).  As a currency union, monetary rules are created and maintained by the European Central Bank.