The United States Air Force organizes enlisted and officer personnel into a dual hierarchy: pay grades (E‑1 through E‑9 for enlisted, O‑1 through O‑10 for officers) and rank titles such as Airman, Staff Sergeant, or Colonel. Pay grades are defined by the Department of Defense’s military pay tables, which adjust annually for cost‑of‑living changes. Rank, by contrast, conveys the individual's position in the chain of command and is reflected in uniform insignia.
Because the two systems run in parallel, a single rank can appear at multiple pay grades over a career. For example, an enlisted Airman may advance from E‑1 to E‑4 while retaining the rank of Airman Basic, Airman, Airman First Class, and finally Senior Airman. Conversely, a newly commissioned Second Lieutenant starts at O‑1, but the same rank title moves up to O‑2, O‑3, and so on as the officer gains experience and time‑in‑grade.