A colonel is a senior military officer rank, typically found in the armies of many countries. In the United States Army, Air Force, and Marine Corps, a colonel ranks above a lieutenant colonel and below a brigadier general. Colonels often command a regiment or brigade and are responsible for planning and executing military operations. The term "colonel" originates from the Italian word "colonnello," which means "chief of a column." This rank is also used in other branches of the military, such as the Royal Air Force and Navy, where it may have different responsibilities and titles.