The Fed, Federal Reserve System, is the central banking system of United States whose objectives, according to the documentation of the entity, is to make the monetary policy decisions of the country, supervise and regulate banking institutions, maintain the stability of the financial system and provide financial services to deposit institutions, the government of the United States and official foreign institutions.
In other words, it is the Central Bank of the United States. It was created in 1913 through the Federal Reserve Act, mainly as a response to a series of financial panics, especially the one of 1907.