Lubrication is the process or technique employed to reduce friction between, and wear of one or both, surfaces in proximity and moving relative to each other, by interposing a substance called a
lubricant in between them. The lubricant can be a solid, (e.g.
Molybdenum disulfide MoS
2) a solid/liquid dispersion, a liquid such as
oil or water, a liquid-liquid dispersion (a
grease) or a gas.