The Joint Chiefs of Staff (JCS) is a group of senior military leaders in the United States. It includes the heads of the five armed services: the Army, Navy, Air Force, Marine Corps, and Coast Guard. The JCS advises the President and the Secretary of Defense on military matters and helps coordinate military operations. The JCS is led by the Chairman of the Joint Chiefs of Staff, who is the highest-ranking military officer. The group plays a crucial role in national defense strategy and ensures that the different branches of the military work together effectively during operations and planning.