This includes their digital equivalent in bank and credit card statements and Treasury-issued base metal coins. As a unit of account, all goods and services, and land and labor are priced in U.S. dollars. Declared legal tender, Federal Reserve notes are the country’s medium of exchange.

This year marks the 100th anniversary of the Federal Reserve System. It is the third central bank in the country’s history. The first two were short-lived compared to the Fed. The First National Bank, chartered in 1791, lasted 20 years, as did the second one, from 1816 to 1836.

When the Fed opened its doors for business in 1914 and for a while thereafter, until 1933, gold was money. People used gold coins to make purchases and pay debts—Double Eagles ($20 Liberties, minted 1850-1907; and $20 St. Gaudens, 1907-1933), Eagles ($10 Liberty Head, minted 1838-1907; and $10 Indian Head, 1907-1933), and $5 Half Eagles (1795-1929).