Tribology is the science and technology of controlling friction and wear.
The subject originated from the art of lubrication but has since developed to a much broader range of applications. Most mechanical equipment is subject to damage by wear or , else, wastes energy by frictional dissipation. Classic illustrations of this rule are found in the domestic motor vehicle. Almost half of the mechanical power generated by the engine is wasted in friction between pistons and cylinders and within the gearbox and transmission gears. The sole purpose of the complicated system of engine cooling, i.e. a radiator, pump and channels within the engine block, is to provide sufficiently low temperatures for the lubricating oil.