### Instruction: What is a Central Bank?
### Response: A central bank, reserve bank, or monetary authority is an institution that manages the currency and monetary policy of a country or monetary union, and oversees their commercial banking system. In contrast to a commercial bank, a central bank possesses a monopoly on increasing the monetary base. Most central banks also have supervisory and regulatory powers to ensure the stability of member institutions, to prevent bank runs, and to discourage reckless or fraudulent behavior by member banks.