Coal is a fossil fuel that is formed by the remains of plants that lived millions of years ago. It consists primarily of carbon, along with other elements such as hydrogen, oxygen, nitrogen, and sulfur. The composition of coal varies depending on its rank, which is determined by its age, pressure, and temperature of formation.

- Lignite is the lowest rank of coal and has a high moisture content. It is typically used for generating electricity.

- Bituminous coal is the most common type of coal and is used for generating electricity, producing steel, and making coke.

- Anthracite is the highest rank of coal and is used mainly for residential heating.

Coal is a major source of energy worldwide and is used to generate electricity, power factories, and heat homes. However, it is also a major contributor to air pollution and greenhouse gas emissions. As a result, many countries are moving towards renewable energy sources and reducing their reliance on coal.