1) The Olympic Games, originating in ancient Greece, were revived in 1896 and are now held every four years, bringing together athletes from around the world.

2) International relations encompass the study of relationships between nations, including diplomacy, treaties, and foreign policy. It examines the interactions and dynamics among different countries in the global arena.

3) Cyclones are fueled by warm ocean waters and atmospheric conditions that allow the formation of thunderstorms.

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