The Army Combat Uniform (ACU) is the current combat uniform worn by the United States Army, U.S. Air Force, and U.S. Space Force. Within U.S. Air Force and U.S. Space Force, it is referred to as the OCP Uniform, rather than the Army Combat Uniform.

A combat uniform, also called field uniform, battledress or military fatigues, is a casual type of uniform used by military, police, fire and other public uniformed services for everyday fieldwork and combat duty purposes, as opposed to dress uniforms worn in functions and parades. It generally consists of a jacket, trousers and shirt or T-shirt, all cut to be looser and more comfortable than more formal uniforms. Design may depend on regiment or service branch, e.g. army, navy, air force, marines, etc. In the army branches, fabrics tend to come in camouflage, disruptive pattern or else green, brown or khaki monochrome, in order to approximate the background and make the soldier less visible in nature. In Western dress codes, field uniform is considered equivalent to civilian casual wear. As such, field uniform is considered less formal than service dress uniform, generally aimed at office or staff use, as well as mess dress uniform, and full dress uniform.