Lubricant

A lubricant is a substance introduced between to surfaces to lessen the friction between them. Lubricants has been used since prehistoric times for example on wheel axels, and see extended use in many industrial applications.

Common lubricants include:

• Petroleum based oils.
• Vegetable fat based oils.

Another way to reduce friction is the use off [ball bearing]?s, which at the time of its invention was revolutionary.