You just imagine sledding without snow. It is not an easy task. While moving, you have to push hard to make the sled move through the surface. The frictional force is responsible for that. Friction is the force that slows objects down when they rub together. Rough things like grass, create more friction than smooth things like snow. Mainly there are four types of friction such as static, kinetic,sliding and rolling friction. Static friction is nothing but the force which holds an object in place when they are not moving. Kinetic friction is the force that slows down moving objects. Rolling friction occurs when a round object rolls across a surface.
Friction is the force that opposes motion between two surfaces that are touching each other. The amount of friction depends on two factors: the kinds of surfaces touching each other and the amount of force pressing the surface together.