This year’s Nobel Prize for Physics went to Albert Fert (France) and Peter Grünberg (Germany), who share the prize fifty:fifty for their discovery of giant magnetoresistance in which a very weak magnetic change gived rise to a major difference in electrical resistance of a system.
This effect underpins the technology that is used to read data on hard disks. It is thanks to their discovery that it has been possible to miniaturize hard disks so radically in recent years. Sensitive read-out heads are needed to be able to read data from the compact hard disks used in laptops and mp3 players, for instance.
You can read more details on the Nobel site here