MRAP stands for Mine-Protected Ambush-Resistant vehicle. In the Iraq War and Afghanistan War (2001-), the U.S. military recognized that improvised explosive devices were causing excessive casualties even in field-armored HMMWVs and other tactical trucks.
The basic IED protection of an MRAP is twofold: they have high ground clearance, giving more distance from an explosion, and they have a V-shaped bottom, which deflects the blast away from the crew compartment. They come in 4-wheel Category I and 6-wheel Category II/III versions.
While Stryker medium and M2 heavy armored fighting vehicles had better protection than the HMMWV, the larger, more expensive vehicles could not be in enough places, and, especially the Bradley were too large to maneuver in old cities.
Two versions went into service in 2003, the Category II Cougar vehicle family and the Category III Buffalo vehicle family, both with combat engineer missions.
A number of other contracts were issued in 2007; approximately 8800 of all versions are on order.
The Buffalo family is based on South African designs. The U.S. Army had started evaluating foreign mine-resistant vehicles in 1999.