The economic and monetary union of the European Union is the currency union (built on a single market) of the European Union members who have adopted the euro as their sole legal tender. Full economic and monetary union has been in effect since 1 January 2002 for twelve countries, with further members joining since. For the European Union, economic and monetary union (EMU) was established in three phases: coordinating economic policy, achieving economic convergence (that is, their economic cycles are broadly in step) and culminating with the adoption of the euro.

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