A plain bearing works by sliding action. This group encompasses most types other than rolling-element bearings. They are often referred to as "sleeve" or "thrust bearings," terms that designate whether the bearing is loaded radially or axially.

Lubrication is important, so their application and function is also often referred to according to the type of lubrication principle used. Thus, terms such as hydrodynamic, fluid film, hydrostatic, boundary lubricated, and self-lubricated are designations for particular plain bearings.