Fly ash is a fine powder that is a byproduct of burning coal in electric power plants. It is collected from the flue gases and consists mainly of silica, alumina, and iron. Fly ash is often used in construction materials, such as concrete, to improve strength and durability. In addition to its use in construction, fly ash can help reduce the environmental impact of landfills by recycling waste materials. It can also enhance the performance of cement and reduce the amount of energy needed for production. Overall, fly ash plays a significant role in sustainable building practices.