thumb|250px|A Polish [[BWP Borsuk amphibious tracked infantry fighting vehicle, armed with 30mm Mk44S Bushmaster II autocannon.]]
thumb|250px|A Russian [[BMP-3, armed with a 2A70 100 mm low-pressure rifled cannon, with embarked infantry. The gun is capable of launching the high-explosive fragmentation projectiles, as well as the 9M117 Bastion gun-launched anti-tank guided missiles.]]
An infantry fighting vehicle (IFV), also known as a mechanized infantry combat vehicle (MICV), is a type of armoured fighting vehicle designed both to transport infantry into battle and to provide direct fire support, combining the function of an armoured personnel carrier (APC) with that of an assault gun/light tank. The 1990 Treaty on Conventional Armed Forces in Europe defines an infantry fighting vehicle as "an armoured combat vehicle which is designed and equipped primarily to transport a combat infantry squad, and which is armed with an integral or organic cannon of at least 20 millimeters calibre and sometimes an antitank missile launcher". IFVs often serve both as the principal weapons system and as the mode of transport for a mechanized infantry unit.
The IFV rapidly gained popularity with armies worldwide due to a demand for vehicles with higher firepower than APCs that were less expensive and easier to maintain than tanks.|name=ASK|group=note These two trends led to the IFV, with firing ports in the troop compartment and a crew-operated weapons system.
During the 1950s, the Soviet, US, and most European armies had adopted tracked APCs. The AMX-VCI was the first purpose-built IFV, renamed from AMX-VTT in 1957, One year before German SPz-12-3, the second true IFV.
The 's doctrine called for mounted infantry to fight and maneuver alongside tank formations rather than the previously well-known heavy armor doctrine. AMX-VCI could carry ten troops in addition to a three-man crew.
As the AMX-VCI and SPz-12-3 were being inducted into service, the Austrian army adopted new APCs which possessed firing ports, allowing embarked infantry to observe and fire their weapons from inside the vehicle. Following the trend towards converting preexisting APCs into IFVs, the Dutch, US, and Belgian armies experimented with a variety of modified M113s during the late 1960s; these were collectively identified as the AIFV (Armored Infantry Fighting Vehicle). In addition to being amphibious and superior in cross-country mobility to its predecessors, the BMP-1 carried a 73mm smoothbore cannon, a co-axial PKT machine gun, and a launcher for 9M14 Malyutka anti-tank missiles.]]
Wheeled IFVs did not begin appearing until 1976, Unlike European IFVs, the Ratel was not designed to allow mounted infantrymen to fight in concert with tanks but rather to operate independently across vast distances. It also identifies all IFVs as having some characteristics of an APC and a light tank.
As asymmetric conflicts become more common, an increasing concern with regards to IFV protection has been adequate countermeasures against land mines and improvised explosive devices. Although the Ratels succeeded in destroying a large number of Angolan tanks and APCs, they were hampered by many of the same problems as the BMP-1: mediocre standoff ranges, inferior fire control, and a lack of stabilized main gun. The Ratels' heavy armament also tempted South African commanders to utilize them as light tanks rather than in their intended role of infantry support.