The Role of High Officials in the Military: Who's the boss?

I've been researching the different military branches as I'm considering enlisting after graduation. Who is considered the head of the military and what kind of responsibilities do they have? Any clarifications will be really appreciated. Thanks!

The head of the military in the United States is the President, who holds the title of Commander-in-Chief. The President has ultimate authority over the military and is responsible for final decisions in matters of defense and national security. The President's roles include deciding where troops will be deployed, how weapons will be used, and strategies for national defense.

Below the President in the chain of command is the Secretary of Defense. The Secretary of Defense is a civilian appointed by the President, and they oversee the Department of Defense, which includes all branches of the military. They advise the President on military policy and strategy, manage the defense budget, and oversee military operations.

Each branch of the military also has a service secretary (like the Secretary of the Army or the Secretary of the Navy) who is responsible for the administration of their specific branch. These service secretaries report directly to the Secretary of Defense.

Within the military itself, the highest-ranking military officer is the Chairman of the Joint Chiefs of Staff. The Chairman serves as the primary military advisor to the President, Secretary of Defense, and National Security Council. However, they do not have operational command authority over the military; instead, they facilitate communication between the different branches of the military and coordinate joint operations.

Remember, the U.S. military operates under the principle of civilian control, meaning that civilian officials -- the President and the Secretary of Defense -- have ultimate authority over the military. This ensures that the military is accountable to the democratic leadership of the country.