A hard disk platter's spinning motion creates a cushion of air above the read/write head, which ensures that the read/write head makes contact with the platter surface instead of floating above the platter.

Question

Quizplus · Accepted Answer

The spinning motion of the platter actually creates a thin layer of air, known as the air bearing, which lifts the read/write head slightly above the surface of the platter. This is necessary to prevent the head from physically touching the surface and causing damage.

A Hard Disk Platter's Spinning Motion Creates a Cushion of Air