A component that reads (senses) and writes (records) data on a magnetic disk or magnetic tape. For writing, the surface of the disk or tape is moved past the read/write head. By discharging electrical impulses at the appropriate times, bits are recorded as tiny, magnetized spots of positive or negative polarity.
For reading, the surface is moved past the read/write head, and the bits that are present induce an electrical current across the gap. See hard disk
Thin Film Read/Write Head
The read/write heads on today's magnetic disks are so tiny you need a magnifying glass to see them. The heads are attached to a pair of aerodynamically designed rails, known as a "slider," that keep the head at the proper distance from the disk platter.
GMR and Inductive Technologies
Typical read/write heads use a giant magnetoreresistive (GMR) head for reading and an inductive coil for writing as in this illustration. (Illustration assistance courtesy of Hitachi Global Storage Technologies.)