The National Security Act is a law enacted in the United States in 1947 that reorganized the country's military and intelligence agencies. It established the Department of Defense, which combined the Army, Navy, and Air Force under a single department to improve coordination and efficiency. The act also created the National Security Council to advise the President on security matters. Additionally, the National Security Act led to the formation of the Central Intelligence Agency (CIA), which is responsible for gathering and analyzing national security information from around the world. This legislation aimed to address the challenges of the post-World War II era and ensure a more unified approach to national defense.