The term "federal reserve banks" refers to the 12 central banks in the United States that make up the Federal Reserve System. However, there are several other names that are used to refer to these banks. One of the most common synonyms is simply "the Fed," which is short for the Federal Reserve System. Other synonyms include "central banks" or "reserve banks" since they are the banks that hold the legal reserve requirements for depository institutions. Another term used is simply "the System" or "the Federal Reserve System," which refers to the governing body that oversees the operations of the reserve banks. Regardless of the synonym used, the federal reserve banks play a critical role in the U.S. economy.