Coal is formed from the degradation of dead remains of plants that get sunk into water over millions of years ago. They were subjected to under high temperature and pressure. The buried plant material is then converted into peat, which is low-grade coal and spongy brown in appearance.Over time, more soil piled up into peat and due to high pressure and temperature, it is converted into lignite also known as brown soil. With the more layers of accumulation over lignite, it is finally converted into bituminous coal and anthracite. They are considered as higher grades coal.

Most of the coal is buried deep under the ground. It is obtained by a process called mining. During mining, big tunnels called mine shafts are dug down to reach the sites of coal. Machines dig the coal and carry it to the surface. Some mine shafts are almost 1,000 feet deep. This is called deep mining. Sometimes the mine may be close to the surface of Earth. In such cases, surface mining is performed. After mining, the coal is cleaned and sold.

Most of the coal is buried deep under the ground. It is obtained by a process called mining. During mining, big tunnels called mine shafts are dug down to reach the sites of coal. Machines dig the coal and carry it to the surface. Some mine shafts are almost 1 , 000 feet deep. This is called deep mining. Sometimes the mine may be close to the surface of Earth. In such cases, surface mining is performed. After mining, the coal is cleaned and sold.