Federal Reserve Notes are paper currency issued by the Federal Reserve System (FED) and circulated by the Federal Reserve Banks. They serve as liabilities of the Federal Reserve Banks and constitute obligations of the U.S. government.
Fiat money is a type of currency that is made legal tender by government law or regulation, without backing by a physical commodity like gold or silver. Its value derives from the trust and authority of the government that issues it.
Inconvertible money is a type of currency that cannot be exchanged for precious metals or other commodities that generally serve as backing for money. Examples include Federal Reserve notes in the United States.
