A bearing is a component of the machine that limits relative movement and reduces the friction between the moving components of a machine to get the motion you want. For example, a spinning fan is assisted by a bearing while noise and vibrations are minimized and the motions are restricted to a radial axis.

The main objective of the bearings is to avoid interaction between two elements in the relative motion between direct metal-to-metal. This avoids friction, heat production, and the wear and tear of parts eventually. It also decreases energy usage as low friction-rolling substitutes for sliding motion.

The load of the rotating element is transmitted to the housing. The load may be radial, axial, or mixed. A bearing also limits the movement of moveable pieces in the above-mentioned directions.