The European Monetary Union (EMU) is a group of European Union (EU) member states that have adopted the euro as their common currency and have established a monetary union with a single central bank, the European Central Bank (ECB). The EMU was established in 1999 and currently consists of 19 of the 27 EU member states. The EMU has a number of institutions that oversee its monetary policy and financial stability, including the ECB, the Eurogroup (which is made up of the finance ministers of the EMU member states), and the European Stability Mechanism (ESM), which provides financial assistance to EMU member states in crisis situations.