Fire retardant can be the fire proof element. It is a substance that reduces flammability of fuels or delays their combustion. Fire retardants may also be coatings that is applied to an object such as a spray retardant to prevent Christmas trees from burning. It includes chemical agents, but may also include substances that work by physical action, such as cooling the fuels, such as fire-fighting foams and fire-retardant gels. Fire retardants are commonly used in fire fighting.