Friction is a force that resists motion between two surfaces that are in contact with each other. It is caused by the microscopic roughness of the surfaces and the interlocking of their irregularities.
Friction can be measured using a device called a frictionometer, which measures the force required to move one object over another. The unit of measurement for friction is called the coefficient of friction.
The three main types of friction are static friction, kinetic friction, and rolling friction. Static friction occurs when two surfaces are not moving relative to each other, kinetic friction occurs when they are moving, and rolling friction occurs when one surface is rolling over another.
Friction can either help or hinder motion. It can help by providing necessary traction for walking or driving, but it can hinder by creating resistance and slowing down moving objects. In some cases, friction can also cause wear and tear on surfaces.
Friction can be reduced by using lubricants, such as oil or grease, between two surfaces. It can also be reduced by using smoother surfaces or by adding rollers or wheels to reduce direct contact between surfaces. However, in some cases, friction is necessary for proper functioning, so it cannot always be completely eliminated.