The modern USAF formally began operations on September 18th, 1947 following the conclusion of World War 2 (September 2nd, 1945) but maintains a history as far back as 1907. Prior to 1947, the USAF operated as the "United States Army Air Forces" (USAAF) and the service contributed to both World War 1 (1914-1918) and World War 2 (1939-1945). The modern United States Air Force has seen major combat actions since the Korean War (1950-1953) and fields a variety of aircraft to cover all manner of mission types.
NOTES: The Five Star rank is generally reserved for wartime only and can also be used as an honorary rank. Formally, USAF rank abbreviations are not displayed with an ending period. Additionally, the USAF does not maintain a First Sergeant rank common to other branches of American service. Instead, the rank is denoted by the special addition of a diamond within the insignia and observed as a duty / job title. Similarly, the diamond is replaced by a star for the Chief Master Sergeant and Command Chief Master Sergeant ranks.