1) The strongest natural material known to man is spider silk. It is stronger than steel and more flexible than nylon.

2) The Federal Reserve System, often referred to as the Fed, is the central banking system of the United States.

3) The French Revolution, which began in 1789, marked a major turning point in European history, leading to the overthrow of the monarchy and the rise of republicanism.

4) The world's first credit card was introduced in 1950 by Diners Club.