Rebar, short for "reinforcing bar," is a steel bar or mesh used as a tension device in reinforced concrete and masonry structures. It is typically made from carbon steel and has ridges or deformations on its surface to enhance the bond between the rebar and the concrete. Rebar is available in various sizes and grades, with the most common being #3 through #11.

Rebar is used to provide reinforcement and strength to concrete structures, such as buildings, bridges, highways, and foundations. It helps to resist tension forces and prevent cracking or failure in the concrete. Rebar is often placed in a grid pattern within the concrete, providing added strength and stability to the structure. Proper placement and spacing of rebar are crucial to ensure the structural integrity of the concrete element.