Jet aircraft are aircraft with jet engines. Generally, jets fly near the top of the troposphere, just below the stratosphere.
The first jetplane was the Heinkel He 178 (Germany), piloted by Erich Warsitz in 1939.
The first jet fighter was the Messerschmitt Me 262, piloted by Fritz Wendel. It was the fastest conventional airplane of WW II (the rocket-powered Messerschmitt Me 163 Komet was faster). Mass production started in 1944, too late for a decisive impact.
During the Korean War on November 8, 1950, United States Air Force Lt. Russell J. Brown flying in an F-80, intercepted two North Korean MiG-15s near the Yalu River and shot them down in the first jet-to-jet dogfight in history.
See also: Commercial aviation