Coal is a black or brownish-black sedimentary rock primarily composed of carbon. It is formed from the remains of ancient plants that have been subjected to heat and pressure over millions of years. Coal is mainly used as a fuel source for electricity generation and in industrial processes, such as steel production. Metals, on the other hand, are elements that are typically shiny, malleable, and good conductors of heat and electricity. Common metals include iron, copper, and aluminum. They are used in a wide range of applications, from construction to electronics, due to their strength and durability.