How does a hard drive store data permanently?

A hard drive stores data permanently using magnetism. The drive contains one or more spinning platters coated with a magnetic material. A read/write head floats just above the surface and magnetizes tiny regions of the coating in one of two orientations, representing binary 1s and 0s. These magnetic states remain stable without any power, which is why the data persists when the drive is turned off. The platters spin at high speed while the head moves across them to access different locations. A motor and actuator arm position the head precisely. Because the magnetic orientations hold their state indefinitely unless deliberately changed or exposed to a strong external magnetic field, the data remains intact until overwritten or erased.