Miniature Ball Bearings are useful in a wide variety of applications. Bearings in general are devices that allow parts to move relative to one another in a constrained fashion. This motion may be linear or in rotation.
A Ball Bearing can be highly effective at reducing friction between two parts that need to move freely.
There is some elasticity to the ball allowing it to support and move a range of bearing loads. Naturally, the balls in such bearings come in a variety of different sizes, from fairly large to miniature. Small Bearings can be extremely useful in applications where space is limited, such as automotive, electrical and medical devices.