Magnetoresistance is a phenomenon where the electrical resistance of a material changes when exposed to a magnetic field. This effect occurs in various materials, including metals and semiconductors, and is particularly significant in certain alloys and compounds. The change in resistance can be used to enhance the performance of electronic devices, such as sensors and memory storage. There are different types of magnetoresistance, including ordinary magnetoresistance and giant magnetoresistance. Ordinary magnetoresistance is observed in most conductive materials, while giant magnetoresistance is much larger and is commonly utilized in hard disk drives and magnetic sensors. This property has important applications in modern technology.