Prefabricating concrete is a method in which concrete is filled into moulds and left to cure. In other word, precast concrete is the product created after concrete has been poured into moulds and left to harden. Concrete is cured by being left to harden in a temperature that does not evaporate the liquid content in the concrete. This process of curing concrete makes it stronger and long lasting. Companies that manufacture precast concrete use moulds of various shapes to create those shapes in concrete. Since these concrete shapes are made before hand and then installed at the construction site they are called precast or prefabricated concrete. Girders of bridges, pillars and other such structures required to complete a building is made out of precast concrete.