From lowest to highest, the ranks of the U.S. Navy are ensign, lieutenant junior grade, lieutenant, lieutenant commander, commander, captain, real admiral lower half, real admiral upper half, vice admiral, admiral and fleet admiral. The highest rank in the U.S. Navy, the fleet admiral, is reserved for war time only.
The last fleet admirals were commissioned in World War II. However, this rank still exists in the list of navy rankings and can be re-established at the discretion of the president and Congress.
In addition to officer ranks, the U.S. Navy also has entry-level ranks for sailors. In order from lowest to highest, these ranks are seaman recruit, seaman apprentice, seaman, petty officer third class, petty officer second class, petty officer first class, chief petty officer, senior chief petty officer, master chief petty officer, command master chief petty officer and master chief petty officer of the navy. There are also warrant officers and commissioned officers. Their ranks from lowest to highest are chief warrant officer 2, chief warrant officer 3, chief warrant officer 4 and chief warrant officer 5.
An officer's rank determines her duty, responsibilities, promotion details and salary. It is possible to know the rank of an officer by looking at the insignia she wears on her uniform.