Why does friction occurs?

Answer 1

Friction is a force which always acts opposite to the force applied on the surface of a body. This opposing force is necessary for many day-to-day activities. Had friction not been there, you wouldn't have been able to walk, write, drive, etc.

There are various ways of increasing or decreasing friction. Lubrication, use of ball bearings, use of anti-friction alloys, use of compressed air, etc are some of the ways of decreasing friction.

While roughening the surface, drying the surface etc are the ways of increasing friction.

Friction occurs because the surface of any object is rough.
No surface is completely smooth, they are rough (if not visibly, then microscopically). When they touch each other, the ridges catch on each other, producing heat/friction.
because when 2 objects rub together it makes a force that interacts with the other object.

Answer 2

Friction occurs when two surfaces rub against each other, causing resistance to their motion. This resistance is due to the microscopic roughness of the surfaces, which creates intermolecular forces. These forces require energy to overcome, resulting in heat and the feeling of friction.

Answer 3

To avoid collisions