The Boeing 737 is an American short to medium range, single aisle, narrow body jet airliner. Developed from Boeing's 727 and 707, the 737 is now available in a number of versions, from the -200 to the most recent addition, the -900ER.

First envisioned in 1964, the 737 entered service in 1968, and 25 years after the announcement of its first sale it has become the most ordered and produced commercial passenger jet in the world. Continuously manufactured by Boeing since 1967 with over 7,000 ordered and over 5,000 delivered (as of 2007), there are over 1,250 of the type airborne at any given time. On average, a 737 departs or lands somewhere every five seconds.