A flag officer is a commissioned officer in a nation's armed forces senior enough to be entitled to fly a flag to mark the position from which the officer exercises command. The term usually, but not exclusively, refers to the senior officers in an English-speaking nation's navy, specifically those who hold any of the admiral ranks; in some cases it applies also to those holding the rank of commodore. In US usage it is additionally applied to Coast Guard officers and general officers in the Army, Air Force, and Marine Corps entitled to fly their own flags.