Rebar, short for reinforcing bar, is a steel rod or mesh used to strengthen concrete structures. Concrete is strong in compression but weak in tension, so rebar helps to absorb tensile forces, preventing cracks and structural failure. It is commonly used in construction projects like buildings, bridges, and roads. Rebar comes in various sizes and grades, with surface patterns that help it bond effectively with concrete. It is often placed in grids or specific patterns before the concrete is poured. The use of rebar enhances the durability and longevity of concrete structures, making it a vital component in modern construction.