Lubricants reduce friction because they eliminate the contact resistance between two solid surfaces or objects. When two solid surfaces come into contact, such as a sled being dragged across a floor, friction is the force that develops. This friction resists the relative motion between the two surfaces that are in contact.
Besides reducing friction, some other advantages of using a lubricant, especially in machinery or an engine, include a reduction in the wear and tear between machine parts and the lowering of their operating temperatures. When a part has a high operating temperature, this can lead to failure. Another benefit of using a lubricant is that it can help prevent parts from corroding.
There are different types of lubricants including oils, greases and gases. Some lubricants that are classified as oils include mineral oil and emulsions.