Coal is a sedimentary rock formed from organic deposits, primarily plant remains, that have undergone the coalification process over a very long geological time. This process involves complex physical and chemical changes under high pressure and temperature. The main components of coal are carbon, hydrogen, oxygen, nitrogen, and sulfur. Based on the level of coalification, coal can be classified into several types, such as peat, lignite, bituminous, and anthracite. The higher the degree of coalification, the higher the carbon content and the lower the water and volatile matter content.

For centuries, coal has been a crucial fossil fuel source for human civilization. Its high energy content and abundant availability make coal a primary fuel for electricity generation, steel production, cement manufacturing, and various other industrial processes. However, large-scale utilization of coal also presents serious environmental issues, such as greenhouse gas emissions contributing to climate change, air pollution, and environmental degradation. The challenge moving forward is to manage coal resources sustainably, mitigate its negative environmental impacts, and find cleaner and more eco-friendly energy alternatives to meet the world’s growing energy needs.