Colossal Magnetoresistance (CMR) is a phenomenon observed in certain materials, particularly in manganese oxides, where their electrical resistance changes dramatically in the presence of a magnetic field. This effect can lead to resistance changes of several orders of magnitude, making these materials useful in various applications, including magnetic sensors and data storage devices. The CMR effect is closely related to the alignment of electron spins and the movement of charge carriers within the material. When a magnetic field is applied, it can enhance the conductivity of the material, allowing for more efficient electronic devices. Researchers continue to study CMR to improve its applications in technology.