Navy ranks begin with Chief Warrant Officers and end with Fleet Admiral, a wartime-only rank. In between are junior officers -- Ensigns, Lieutenants Junior Grade, Lieutenants, Lieutenant Commanders -- and senior officers -- Commanders and Captains. Rear Admiral, Lower and Higher Half, Vice Admiral and Admiral complete the ranks.
Only enlisted sailors with a minimum of 13 years service and a top tier pay grade may apply for rank of Warrant Officer. The rank of Ensign is the entry level rank for a commissioned officer requiring graduation from the Naval Academy or completion of Officer Candidate School or Naval Reserve Officer Training Corps. Ensigns move to Lieutenant Junior Grade in about two years.
Officers in the three lieutenant ranks move from specialty training and work as Fleet Division Officers or Division Officers on smaller ships to Department Head or Executive Officer on larger ships. As rank increases, so do depth of responsibility, breadth of command and level of accountability. Commissioned officers serve at the pleasure of the president, and promotions must have Senate approval.
Rate, not rank, is used to refer to enlisted sailors. Seaman Recruit is the lowest enlisted rate. Master Chief Petty Officer of the Navy is the highest rate.