What causes friction ?

If any object that is in motion comes to rest at a certain point of time.This happens due to friction.Friction is caused when two objects rub against each other. For example : A ball is being rolled and due to the friction caused between the ground and the ball it comes to a stop. There are 3 types of friction: *Static friction *Sliding friction * Rolling friction STATIC FRICTION is caused when an object in motion comes to a stop earlier due to the hard surface. SLIDING FRICTION is caused when an object slides on the surface.Here the friction is less compared to static friction. ROLLING FRICTION is caused when an object rolls over the surface .Here the friction is very less compared to other 2 frictions. Friction becomes higher when : *Shoes are fit with spikes at the bottom. *When brakes are applied in a vehicle. * When the surface in which the object moving is uneven and is very rough. Friction becomes lesser when: *Lubricants are used. *Usage if ball bearings * Usage of air cushion