The Boeing 737 family is the most successful airliner lineage in the world. Orders for the first-generation Boeing 737-100 and 737-200 were placed in 1965 and since then, over 6,000 aircraft were produced.
The family consists of three generations of aircraft. The earliest was the Boeing 737 Original (which included the Boeing 737-100, -200 and -200 Advanced), followed by the Boeing 737 Classic series (including the Boeing 737-300, -400 and -500) and the Boeing 737 Next Generation, or Boeing 737 NG (including the Boeing 737-600, -700, -800 and -900).
Boeing 737 Original series which include the highly popular Boeing 737-200, as well as its somewhat less successful brother, the -100, and its updated version, the Boeing 737-200 Advanced, were designed for short- to medium-range flights. These early models of the 737 were manufactured from 1967 to 1985, totaling 1,831 aircraft.
Near the beginning of the 80s, the 737 was updated with newer CFM56 engines and digital avionics, which gave rise to the Boeing 737 Classic series. The success of the first plane in the new series, the 737-300, in turn led to the development of two other versions: the 737-400, with a longer fuselage and more carrying capacity, and the 737-500, a shorter variant with a greater range. Between 1984 and 2000 almost 1,990 planes of the Boeing 737 Classic series were produced.
1997 saw the introduction of the new and improved Boeing 737 NG (Next Generation) series, outfitted with more efficient engines, an updated wing design, featuring a larger area and the ability to mount winglets, and better-equipped passenger sections. These newer planes are capable of achieving faster flight speeds, longer travel distances and more efficient fuel consumption than their predecessors. The Boeing 737 NG series are currently still being manufactured and, alongside the Airbus A320 family, are the most common medium-range airliners in the world.
Presently, the Boeing Corporation is developing a new generation of airliners based on the Boeing 737, under the name of Boeing 737 MAX. Meant to replace the Boeing 737 NG, the new series of jets will include 4 base models: 737 MAX 7 (replacement for Boeing 737-700), 737 MAX 8 (replacement for Boeing 737-800), 737 MAX 9 (replacement for Boeing 737-900) and 737 MAX 10 (with the longest fuselage of all aircraft of the Boeing 737 family). These aircraft received minor modifications to the fuselage and wings, and are also outfitted with new, more efficient engines. The first planes of the 737 MAX entered service in 2017.