What is Air force?
An '''air force''' is the branch of a country's [[military]] which fights in the air. The air force is made up of [[aircraft]] such as [[fighter]]s, [[bomber]]s, [[helicopter]]s and [[transport]] [[aircraft]]. When a [[navy]] has its own air force it is called [[Naval Aviation]]. Air forces began in the early 20th century, usually as part of the [[army]]. Most countries separated their air forces in the 1930s and 1940s. Aircraft in an air force sometimes fly in a [[wikt:formation|formation]]. Formations are when the aircraft fly in a pattern. Air forces is part of the military. The biggest air force in the world is the [[United States Air Force]] (USAF).<ref>{{cite book|title=Report to Congress of the United States: China Economic and Security Review Commission|author=Daniel Slane|year=2010 |page=74|publisher=DIANE Publishing|isbn=9781437943399}}</ref> Second and third largest are the [[United States Navy]] and [[Russian Air Force]]. ==References== {{Commons category|Air force}} {{reflist}} {{Military branches | state = expanded}} {{military-stub}} [[Category:Air force| ]]