Friction

First of all lets consider the example of matchstick or a lighter. You rub your matchstick against the rough surface of the matchbox to ignite it. The head of a matchstick comprises of chemicals that catches fire when subject to high amount of heat. The heat is generated because of the friction originating due to the rubbing of the match head over the rough surface of the matchbox. The surface is purposefully made rough so as to maximise friction. 

Similarly in case of a cigarette lighter, friction of the roller with a piece of metal results in sparks that ignite the fuel.

A wheel rolls on the surface of the road because of friction. Although it must be noted that a wheel is actually designed to minimise friction. It is very difficult to move a body with a flat surface because as the surface area in contact with the road increases, the amount of friction encountered by a body on its motion also increases.

It won't be possible for us to walk without friction. It is because of the friction between our feet and the surface of the road that we are able to stand steadily on a road.

Before the invention of matches the ancient humans used to light fire by rubbing two flint stones against each other. In America, which back then was cutoff from the civilized world, the American natives used to light fire using a bow and a wooden spindle by making it spin against a wooden surface. Again friction played a major part in lighting fire. 

Friction has negative effect as well. Friction between different parts of a machine increases the temperature of the machine and because of that there is wear and tear in different parts of the machine. To overcome this different parts of the machines are oiled from time to time.

In vehicles grease is used to minimise friction between different components. At high temperatures graphite is used as a lubricant and it does the function of minimizing friction between moving parts. The major reason of using graphite in place of oil at height temperatures is that at high temperatures oil may catch fire, but graphite wont. 

Writing on paper is possible because of friction. It is the friction between the paper and pencil that leads to deposition of a layer of graphite over the area from which the pencil passes. If you pour oil over a piece of paper and then if you try to write on it you won't be able to do so since oil would significantly reduce the amount of friction between the paper and pencil/pen.

Mountain climbers when they climb on mountains with lots of snow wear shoes with metal spikes. The metal spikes help them to get a better grip over the surface, since a surface with lot of snow will offer very little friction because of which a person climbing a mountain may slide.

Thus the phenomena of friction is very important and we must use our intelligence to make best use of it.