A cross between a tank and a truck. Most halftracks consist of a large truck frame with two front wheels, but with the rear wheels replaced with tank treads. Halftracks appeared in small numbers at the end of WWI, but found widespread use during the Second World War on both the allied and axis sides, mostly as armored personnel carriers. Some countries still use upgraded surplus versions of these vintage halftracks.
The American M3 series is a good example of a halftrack.