Carbon is found in three forms. In the form of diamond it is the hardest substance in the world. As graphite it is a greasy, grey material that is used to make metals glide over one another. Carbon is also a black substance found when materials burn.

Carbon is also found combined with many other substances. It is found in all living things and in substances such as oil and gas that have been made from living things.

As a result, carbon is found in materials as varied as wood and plastic, wool and cotton. When a material burns some of the carbon that it contained is left behind as a black ash. Think of a burnt match - the black tip is made of carbon.

Coal is a form of carbon formed as plants are heated and squashed when deep underground. Charcoal is a form of carbon made by heating wood without air. Charcoal is used for barbecues and, because it is a soft material that leaves a black trace on paper, by artists for drawing. Soot is the carbon particles that come from burning coal.

Graphite is dark grey and quite soft. Graphite is the black substance in the pencil lead. When you draw a line with a pencil tiny pieces of graphite rub off onto the pencil. If you rub a soft pencil on your skin, you will find that the mark feels greasy - this is the effect of the graphite flakes slipping over one another.

A bonfire (see video below) burns carbon with oxygen from the air to make carbon dioxide gas and give out heat.