basic machine component designed to reduce friction between moving parts and to support moving loads. There are two main types of bearings:

1. rolling contact bearings (also called anti-friction bearings) commonly ball or roller;

2. sliding (plain) bearings, either plain journal (a metal jacket fully or partially enclosing a rotating inner shaft) or pad-type bearings, for linear motion.

Rolling-contact bearings are more effective in reducing friction. With few exceptions, bearings require lubrication to reduce wear and extend bearing life.

Also see Bearing Almanac.