How does friction arise between two surfaces?

A simple reason for the origin of friction can be known as follows. No surface in this universe is perfectly smooth. Every surface has irregularities. read more

Friction arises whenever one body moves or tries to move, over another. Friction is a force between two surfaces, which opposes movement between those surfaces. Work must be done against this force, and this work is converted to heat. The amount of force is affected by the nature of the surfaces. read more

Gravity and friction are the two most common forces affecting our lives. While we know a good deal about gravitational forces, we know relatively little about friction. Frictional forces are believed to arise from the forces of attraction between the molecules in two surfaces that are pushed together by pressure. read more

There are irregularities on any surface unless it is a perfectly smooth surface, and when two surfaces come in contact and one of them tries to move over the other these irregularities mesh up with each other hampering the motion, giving rise to friction. read more