Coal is a black or brownish-black sedimentary rock that is primarily composed of carbon, along with various other elements. It is formed from the remains of ancient plants that have undergone heat and pressure over millions of years. Coal is a major source of energy worldwide, used primarily for electricity generation and steel production. Despite its abundance and low cost, coal has significant environmental impacts, including greenhouse gas emissions and air pollution. As a result, many countries are transitioning to cleaner energy sources. However, coal remains a critical component of the energy mix in many regions, particularly in China and India.