Rebar is short for reinforcing bar and is a type of steel bar that is used to reinforce concrete structures. It is made of high-strength steel and has a rough surface that helps it bond to the concrete. Rebar is placed in concrete before it is poured and provides additional tensile strength to the concrete, helping to prevent cracking and collapse under stress.

Rebar is placed in a grid-like pattern within the concrete, with the bars spaced a certain distance apart and tied together with wire. This helps distribute the stress placed on the concrete evenly, reducing the risk of cracking and failure.

Rebar is an economical way to add strength to concrete structures, as it is relatively cheap and easy to install. It is widely used in construction, particularly in the building of concrete bridges, buildings, and other large structures.

Rebar should not be confused with post-tensioned tendons, which are also used to reinforce concrete structures. Post-tensioned tendons are high-strength steel cables that are placed in a concrete structure and then tightened to create tension. The tension in the tendons helps to hold the concrete together and prevent cracking, making it a useful technique for repairing large concrete structures, such as bridges and high-rise buildings.