A plain bearing, or more commonly sliding bearing and slide bearing (in railroading sometimes called a solid bearing or friction bearing[citation needed]), is the simplest type of bearing, comprising just a bearing surface and no rolling elements. Therefore, the journal (i.e., the part of the shaft in contact with the bearing) slides over the bearing surface. The simplest example of a plain bearing is a shaft rotating in a hole. A simple linear bearing can be a pair of flat surfaces designed to allow motion; e.g., a drawer and the slides it rests on or the ways on the bed of a lathe.

Plain bearings, in general, are the least expensive type of bearing. They are also compact and lightweight, and they have a high load-carrying capacity.

SKF manufactures spherical plain bearings, rod ends and bushings in various designs and with different sliding contact surface combinations. Each design and combination has characteristic properties which makes it particularly suitable for certain applications.