A wheel bearing is a crucial part of the wheel assembly that connects the wheel and the axle. It is a set of steel balls (ball bearings) or tapers (tapered bearings), held together by a metal ring. It enables the wheel to rotate smoothly with a minimum of friction.
Bearings reduce friction by providing smooth balls or rollers, and smooth inner and outer surfaces for the balls to roll against. These balls or rollers “bear” the load, allowing the device to spin smoothly.