In science, a lubricant is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. Lubricants can be in liquid, solid, or plastic form, and they can be made of various substances such as oil, grease, graphite, and molybdenum disulfide. The primary function of a lubricant is to reduce friction and wear between surfaces in contact, but it can also perform other functions such as:

• Temperature control: Lubricants can absorb heat from surfaces and transfer it to a point of lower temperature where it can be dissipated.
• Contaminant removal: Lubricants can work as a conduit to transport contaminants to filters to be removed.
• Shock damping: Lubricants can act as shock-damping fluids in energy-transferring devices and around machine parts that are subjected to high intermittent loads.

There are three different types of lubrication: boundary, mixed, and full film, and each type relies on a lubricant and the additives within the oils to protect against wear.