The military uses ranks to establish levels of authority and responsibility among its airmen, sailors, soldiers and Marines. Ranks are divided into three general categories of enlisted, warrant officer and officer. Ranks correspond roughly to time in service, though performance is an equally significant factor in promotion in the higher ranks. Pay grades are billed as E-1 through E-9, W-1 through W-5 and O-1 through O-10, corresponding to the ranks of the enlisted corps, the warrant officer corps and the officer corps of each service.
Army and Marine Junior Enlisted Ranks
In the Army, junior enlisted soldiers are known in ascending rank as private E-1, private E-2, private first class E-3, specialist and corporal E-4. Specialists and corporals hold the same pay grade of E-4, though corporals are charged with greater responsibility than specialists, serving as team leaders in small units in the Army. The Marines refer to E-2s as privates first class, E-3s as lance corporals and corporals for the pay grade of E-4. Corporals in the Marines also serve as junior non-commissioned officers, otherwise known as NCOs.
Navy, Coast Guard, and Air Force Junior Enlisted Ranks
The Navy and Coast Guard share the same ranking system. The Navy has the ranks of seaman recruit E-1, seaman apprentice E-2, seaman E-3 and petty officer third class E-4. All ranks of petty officers in the Navy are considered NCOs. The Air Force names its junior ranks as airman basic E-1, airman E-2, airman first class E-3 and senior airman E-4.
Army and Marine Non-Commissioned Officer Ranks
Mid-level Army NCOs are ranked as sergeant E-5, staff sergeant E-6 and sergeant first class E-7. From there, there are senior NCOs that share the same pay grades but differ in rank. E-8s are either master sergeants or sergeants first class. E-9s are known as sergeant major or command sergeant major, with the top NCO in the Army holding the rank of sergeant major of the Army. The Marines follow much of the same system, though it titles the rank of E-7 as gunnery sergeant and E-9 as master gunnery sergeant instead of command sergeant major.
Navy, Coast Guard, and Air Force Non-Commissioned Officer Ranks
The Navy calls its NCOs petty officers. Petty officers second and first classes make up the E-5 and E-6 ranks, while E-7 is referred to as chief petty officer. Senior chief petty officer is the title of E-8, and the rank of E-9 holds the rank of master chief petty officer, fleet/command master chief petty officer and master chief petty officer of the Navy. The Air Force has staff sergeants and tech sergeants for grades E-5 and E-6. E-7 has the ranks of master sergeant and first sergeant. E-8 has the ranks of senior master sergeant and first sergeant. The grade of E-9 has four ranks, including chief master sergeant, first sergeant, command chief master sergeant and chief master sergeant of the Air Force.
Every service except for the Air Force has a Warrant Officer Corps. These ranks are all titled as "chief warrant officer," pay grades W-2 through W-5. W-1 is titled simply "warrant officer." Warrant officers serve as highly experienced specialists in their field of work.
Officer ranks in the Army, Marine Corps and Air Force all share the same names. Their order follows O-1 through O-10 as second lieutenant, first lieutenant, captain, major, lieutenant colonel, colonel, brigadier general, major general, lieutenant general and general. The Navy has its own line of rank names. O-1 through O-10 are known respectively as ensign, lieutenant junior grade, lieutenant, lieutenant commander, commander, captain, rear admiral lower half, rear admiral upper half, vice admiral and admiral.