The original M113 Armored Personnel Carrier (APC) helped to revolutionize mobile military operations. The vehicles were able to carry 11 soldiers plus a driver and track commander under armor protection across hostile battlefield environments. More importantly, the new vehicles were air transportable, air-droppable, and swimmable, allowing planners to incorporate APCs in a much wider range of combat situations, including many "rapid deployment" scenarios. The M113s were so successful that they were quickly identified as the foundation for a family of vehicles. Early derivatives included both command post (M577) and mortar carrier (M106) configurations. 

M113A1 Armored Personnel Carrier (1964)

The first major upgrade came in 1964 with the introduction of the M113A1 package which replaced the original gasoline engine with a 212 horsepower diesel package. The new power train was soon incorporated into the existing vehicle family as the M113A1, M577A1, and M106A1, as well as several new derivative systems. Some of these new derivatives were based on the armored M113 chassis (the M125A1 mortar carrier and M741 "Vulcan" air defense vehicle) while others were based on an unarmored version of the chassis (including the M548 cargo carrier, M667 "Lance" missile carrier, and M730 "Chaparral" missile carrier). 

M113A2 Armored Personnel Carrier (1979)

Continuing modernization efforts led to the introduction of the A2 package of suspension and cooling enhancements in 1979. As with previous enhancements, these upgrades resulted in further proliferation of the FOV.

Since their initial introduction in 1960, M113-based systems have entered service in more than 50 countries. The systems have been modified into more than 40 identified specific variants, with many times that number of minor field modifications. Many of these modifications have been developed by foreign governments to meet their specific national requirements. While some older M113 derivatives are being retired and removed from selected inventories, other FOV members are being upgraded, reconfigured, and introduced as entirely new systems. 

More than 80,000 M113 Family of Vehicle (FOV) systems have been produced. New M113 FOV systems are being built while existing chassis are being upgraded to modern configurations. 

One of the lessons learned so costly at the Yom Kippur War (1973) and Lebanon War (1982) was the vulnerability of the armored personnel carrier (APC) in the modern battlefield. The first M113 APC were sold to Israel in 1970 and after that M113 is the main APC in IDF.