Rebar is a kind of steel bar, is a kind of building material. For example, in reinforced concrete, the skeleton is used to support the structure. Steel tensile resistance is not compressive, concrete compressive resistance is not tensile, the combination of the two has a good mechanical strength, steel is protected by concrete without rust, and steel and concrete have approximately the same coefficient of thermal expansion, more will not produce cracks and corrosion, so it has become the ideal material for modern buildings, become widely used reinforced concrete buildings.