The Boeing 707 is a four-engine narrow-body commercial passenger jet airliner developed by Boeing in the early 1950s. Its name is most commonly pronounced as "Seven Oh Seven". Boeing delivered a total of 1,010 Boeing 707s including a smaller, faster model of the aircraft that was marketed as the Boeing 720.
Although it was not the first commercial jet in service, the 707 was among the first to be commercially successful. Dominating passenger air transport in the 1960s, and remaining common throughout the 1970s, the 707 is generally credited with ushering in the Jet Age. It established Boeing as one of the largest makers of passenger aircraft, and led to the later series of aircraft with "7x7" designations.
The Boeing 707 was an outgrowth of the Boeing Model 367-80. The "Dash 80" took less than two years from project launch in 1952 to rollout on May 14, 1954, then first flew on July 15, 1954. It was powered by the Pratt & Whitney JT3C turbojet engine, which was the civilian version of the J57 used on many military aircraft of the day, including the F-100 fighter and the B-52 bomber.
The prototype was conceived as a proof of concept aircraft for both military and civilian use: the United States Air Force was the first customer for the design, using it as the KC-135 Stratotanker midair refueling platform. It was far from certain that the passenger 707 would be profitable. At the time, Boeing was making nearly all of its money from military contracts: its last passenger transport, the Boeing 377 Stratocruiser, had netted the company a $15 million loss before it was purchased by the Air Force as the KC-97 Stratotanker.