Greenspan, Alan (1926-...), an American economist, served as chairman of the Board of Governors of the Federal Reserve System, commonly called the Fed, from 1987 to 2006. The Fed is an independent federal agency that directs the United States banking system and helps control the nation's interest rates and money supply. Greenspan was appointed chairman by President Ronald Reagan. He was reappointed by President George H. W. Bush in 1991, by President Bill Clinton in 1996 and 2000, and by President George W. Bush in 2004. Greenspan is a conservative economist and an advocate of laissez faire, a theory that government should not interfere in most economic affairs.