The Boeing 737 is a short- to medium-range twinjet narrow-body airliner developed and manufactured by Boeing Commercial Airplanes in the United States. Originally developed as a shorter, lower-cost twin-engine airliner derived from the 707 and 727, the 737 has developed into a family of thirteen passenger models with capacities from 85 to 215 passengers. The 737 is Boeing's only narrow-body airliner in production, with the 737 Next Generation (-700, -800, and -900ER) and the re-engined and updated 737 MAX variants currently being built.
The 737 was originally envisioned in 1964. The initial 737-100 made its first flight in April 1967, and entered airline service in February 1968 at Lufthansa. Next, the lengthened 737-200 entered service in April 1968. In the 1980s Boeing launched the longer 737-300, −400, and −500 variants (referred to as the Boeing 737 Classic series) featuring CFM56 turbofan engines and wing improvements.