The Federal Reserve System (also known as the Federal Reserve, and informally as the Fed) is the central banking system of the United States. It was created in 1913, with the enactment of the Federal Reserve Act, and was largely a response to prior financial panics and bank runs, the most severe of which being the Panic of 1907. Over time, the roles and responsibilities of the Federal Reserve System have expanded and its structure has evolved. Events such as the Great Depression were some of the major factors leading to changes in the system.