The Department of Defense, commonly referred to as DoD, is the United States government agency responsible for coordinating and supervising all agencies and functions related to national security and military affairs. Established in 1947, it oversees the U.S. Armed Forces, which includes the Army, Navy, Air Force, Marine Corps, and Coast Guard. The DoD's primary mission is to protect the country and its interests through military readiness and strategic planning. The DoD is headquartered at the Pentagon in Arlington, Virginia, and operates under the leadership of the Secretary of Defense. It plays a crucial role in formulating defense policies, managing military operations, and ensuring the safety of the nation. The agency also collaborates with international allies to address global security challenges.