Hard disk

A hard disk is really a set of stacked "disks," each of which, like phonograph records, Hard disks have diffrent sectors shares data recorded electromagnetically in concentric circles or "tracks" on the disk. A "head" (something like a phonograph arm but in a relatively fixed position) records (writes) or reads the information on the tracks. Two heads, one on each side of a disk, read or write the data as the disk spins. Each read or write operation requires that data be located, which is an operation called a "seek."