The term NAV. RANK refers to the ranks of the United States Navy. The rank of ENS (Ensign) is the lowest commissioned officer rank, followed by ADM (Admiral), CDR (Commander), CPO (Chief Petty Officer), and CMDR (Commodore). Ensigns are typically responsible for leading small units of sailors and junior officers, while Admirals are the highest ranking officers in the Navy and are responsible for commanding fleets and making strategic decisions. Commanders are responsible for leading ships and aircraft squadrons, while Chief Petty Officers are the senior enlisted personnel who provide technical expertise and leadership to their units. Finally, Commodores are senior officers who lead large groups of ships and aircraft squadrons.