Rebar, short for reinforcing bar, is a steel bar or mesh used to reinforce concrete structures. It helps improve the tensile strength of concrete, which is naturally strong in compression but weak in tension. By embedding rebar within concrete, builders can create stronger and more durable structures, such as bridges, buildings, and roads. Rebar comes in various sizes and grades, allowing engineers to choose the appropriate type for specific construction needs. It is often coated with materials like epoxy to prevent rusting, which can weaken the concrete over time. Proper placement and spacing of rebar are crucial for ensuring the integrity of the final structure.