The term “colossal magnetoresistance” (CMR) was coined to describe the mag­ netoresistance observed near the transition from a high temperature paramagnetic insulator to a low temperature ferromagnetic metal in perovskite manganites [1], in analogy to the “giant magnetoresistance” (GMR) observed in magnetic metallic multilayers [2]. GMR arises from the different scattering times and densities of states encountered by majority/minority carrier electrons as they traverse from one magnetic layer to the next, where their identity as majority/minority carriers are projected onto the local orientation of the magnetization. In this sense GMR is a nonintrinsic phenomenon, whereas CMR by comparison is an intrinsic, bulk property.