Friction is a force that dissipates energy. It occurs when sliding an object over a surface. The molecules in the surface bond with the molecules in the body causing the sliding motion to be resisted. This force is directed along the surface and opposite to the direction of the motion. It s friction that enables us to walk, among other things.
Friction is what keeps one foot planted on the ground as the other one steps forward.
Otherwise, without friction, the shift in weight would cause us to slide around. Also most braking systems use friction as their main component. When you squeeze the brakes on a 10 speed bike, a small rubber brake is pressed against both sides of the bike tire. The friction of the brake pad against the wheel causes the rotational energy of the wheel to be dissipated or removed by transfering it to heat and sound energy. Before we can talk about friction in ice skating, we have to know how ice skates are put together.