Prestressed concrete is a type of concrete that is intentionally placed under compression before it is subjected to external loads. This is achieved by using high-strength steel tendons or cables that are tensioned and anchored within the concrete. The compression counteracts the tensile stresses that occur when the structure is loaded, enhancing its strength and durability. This method is commonly used in structures like bridges, parking garages, and high-rise buildings, where large spans and heavy loads are present. By using prestressed concrete, engineers can create thinner slabs and longer spans, reducing the amount of material needed and improving overall efficiency.