Precast concrete is a construction material made by casting concrete in a controlled environment, usually in a factory, before transporting it to the construction site. This method allows for better quality control and faster construction times, as the pieces can be made while site preparation is ongoing. The precast concrete elements can include walls, beams, and slabs, which are designed to fit together easily. This technique is often used in building structures like bridges, parking garages, and residential homes, providing durability and strength while reducing labor costs and construction waste.