The
Air Force is one of the four main units of the
Department of Defense, and operates all of the US military's
bomber aircraft, all of its ground-based
fighter aircraft, and all of its
ballistic missiles. Ship-based fighters and helicopters are under the jurisdiction of the
Navy, and ground-based helicopters and
V/STOL aircraft are under the jurisdiction of the
Army and
Marines.
Because the Air Force was originally a part of the Army, it uses Army ranks and insignia. Its uniforms are different, and many of its customs (salutes etc.) are also different.
Its combat aircraft today are the F-117, F-15, F-16, F-22, A-10, B-1, B-2, and B-52. It also operates cargo planes, tankers, AWACS, and JSTARS aircraft.
In addition to its many bases in the US, it has bases in Britain, Italy, Germany, Turkey, South Korea, and Japan.
Overall, not someone you'd want to pick a fight with.
Organization
The Air Force currently consists of eight operational commands, which are subdivided into numbered air forces, wings, groups, squadrons, and eventually flights. Any of these units can be further subdivided into detachments.
Air Combat Command (ACC), based at Langley AFB, is responsible for the Air Force's bombers and US-based fighters. It is divided into four air forces: 1AF at Tyndall AFB defends the continental United States, 8AF at Barksdale AFB controls bombers and nukes, 9AF at Shaw AFB is the air component of United States Central Command in the Middle East, and 12AF at Davis-Monthan AFB is the combat complement of United States Southern Command.
Air Mobility Command (AMC), based at Scott AFB, is responsible for the Air Force's tanker and airlift aircraft. Its two main divisions are 15AF at Travis AFB, which serves everything west of the Mississippi River and east of Africa, and 21AF at McGuire AFB, which serves the other half of the world.
United States Air Forces in Europe (USAFE) is based at Rammstein Air Base in Germany. 3AF at RAF Mildenhall is responsible for operations north of the Alps, while 16AF at Aviano Air Base in Italy runs operations around the Mediterranean. Other key bases are RAF Lakenheath, Spangdahlem Air Base, and Incirlik Air Base in Turkey.
Pacific Air Forces (PACAF) is based at Hickam AFB. 5AF at Yokota Air Base is responsible for Japan, 7AF at Osan Air Base is responsible for Korea, 11AF at Elmendorf AFB is responsible for Alaska, and 13AF at Andersen AFB is responsible for Micronesia.
Air Force Space Command (AFSPC, not to be confused with the defunct United States Space Command) is based at Peterson AFB. Its two main divisions are 14AF at Vandenberg AFB, which operates Air Force satellites in orbit; and 20AF at Warren AFB, perhaps the deadliest combat unit in the world, operating the United States' ICBM arsenal.
Air Education and Training Command (AETC) at Randolph AFB is where the Air Force's personnel get their skills. 2AF at Keesler AFB trains non-flying servicemen, while 19AF at Randolph trains the pilots. AETC also runs the Air University, Air Command and Staff College, and Air War College, as well as the USAF's many ROTC programs.
Air Force Special Operations Command is the black helicopter arm of the Air Force, and if I say too much about them, guys in suits might show up at my dorm. They are the Air Force's main counterterrorism and unconventional warfare brigade.
Air Force Reserve Command (AFRC) keeps a sizable fleet of surplus airlift and fighter aircraft on hand in case the US goes to war.
There are also several units in the Air Force that fall independent of these major commands: the most notable one is the United States Air Force Academy.