Friction is a force that is created when two surfaces move or try to move across each other. The amount of friction produced during this process depends on the texture (how smooth or rough) of both the surfaces and the amount of contact force pushing the two surfaces together.
Friction always opposes or stops the movement of one surface across another surface. As the two surfaces slide against each other, they rub and produce friction. You will find friction everywhere that objects come into contact with each other.
The force acts in the opposite direction to the way an object wants to slide. When you want to stop your bicycle, you press the brake and your bicycle slows down because of the friction between the brakes and the wheels. If you are running on a playground and hear your friend call you and suddenly want to stop, you can, because of the friction between your shoes and the ground.
Friction produces heat. For example when you rub your hand together they become warm as the kinetic energy from the rubbing changes to heat energy.
We can reduce friction by lubricating a surface with oil or grease and make the surface smoother. We can also reduce friction by adding wheels to an object.
The treads on a tyre is used to increase friction between the tyre and the road so that the tyre does not skid.