"Magnetoresistance is the effect that was discovered long ago (by Lord Kelvin) about how the resistance of a current depends on an external magnetic field. Giant Magnetoresistance is the discovery that one can obtain a much greater effect by having nanometre-thin layers of magnetic and non-magnetic metals stacked on each other. The discovery was made in 1988, but it took until the mid-1990's until the effect was used in applications, and only in recent years has this technology been revolutionizing disk drives for computers."