The Boeing 737 is a narrow-body jet aircraft manufactured by Boeing, designated 737, with two turbofan engines, available in 73s (larger & advanced version 200), 73F (mixed passenger & freight version), 733 (300 series), 734 (400 series) and 735 (500 series). The Boeing 737 is similar to the Airbus A320 & A321, with two engines mounted on the wing, but smaller in size.