When wood is burnt in a limited supply of air, water and other volatile materials present in it are removed, and a black substance called charcoal is left behind.
Charcoal is a better fuel than wood for the following reasons.
1. Charcoal produces more heat on burning than an equal mass of wood.
2. Charcoal does not produce smoke while burning, whereas wood produces much smoke and causes air pollution.
3. Charcoal is a compact fuel that is easy to handle.