Warrant officers in the U.S. Navy are ranked, by number, according to their level of promotion. There are five ranks of warrant officers; those who have been promoted are called commissioned warrant officers.
Warrant officers are at the first level after they receive warrants from their service secretary. They are experts and specialists in abilities and military technology.
Warrant officers become chief warrant officers after they receive a commission from the president. The order of rank is Chief Warrant Officer 2, 3, 4 and 5. After the first promotion, commissioned warrant officers become direct representatives to the president. The presidential authority is the same for commissioned officers, but the warrant officers remain specialists.
Chief warrant officers wear an insignia, noting their expertise, on one sleeve of their dress blue uniforms and on their shoulder boards. The insignia is worn on the left collar and rank strip on the right collar when officers wear Winter Blue and khaki uniforms.
Insignias for technical expertise include those for engineering, ordnance, aviation and data processing. Ability expertise insignias include those for boating, diving and aerography.
After a Chief Warrant Officer 5 is promoted by the president, he becomes a commissioned officer. There are 10 ranks of commissioned officers, with the last four being admirals.