The Boeing 737 is the most produced jet airliner in the world with more than 7,000 built with another 3,000 on order as of mid-2012. The 737 was envisioned as a small, short range airliner to supplement the Boeing 707 and 727. Design work began in 1964 and the prototype first flew in April 1967. Two versions of the 737 were developed simultaneously the -100 and the slightly longer -200. These versions entered service with Lufthansa and United Airlines in early 1968. Since then the 737 has been built in nine different major versions with at least one more variant on the drawing board.

The 737 is in use by large and small airlines around the world. It has been estimated that over 1,000 are flying at any given moment with two more taking off or landing every five seconds. In addition to the commercial versions of the aircraft the U.S. military has used several versions of the aircraft. The T-43A was used by the USAF as a navigation trainer and transport, The C-40 is in use by both the Air Force and the Navy as a cargo and personnel transport. The latest 737 derived military aircraft is the P-8 Poseidon maritime patrol and anti-submarine warfare aircraft.

The 737-300 is the third version of the aircraft built. It was a major redesign of the plane featuring new high-bypass turbofan engines that reduced both noise and fuel consumption. The -300 was announced in 1981 and went into airline service with Southwest Airlines and USAir in 1984. A total of 1,113 of this version were built between 1984 and 1999 when the last one was delivered.