The Department of Defense (DoD) is a part of the United States government responsible for ensuring the country's security. It oversees the nation's military forces, including the Army, Navy, Air Force, and Marine Corps. The DoD develops strategies to protect the nation from threats and coordinates military operations around the world. In addition to managing the armed forces, the DoD also works on defense policy, military research, and technology development. It plays a crucial role in international relations, collaborating with other countries to promote peace and stability. The DoD's efforts help maintain the safety of the American people and support global security initiatives.