A rebar is a bar made out of common steel, which is used in concrete foundations and other masonry structures to reinforce the wall or structure. Rebar is most commonly seen as a long, thin steel bar which has ridges on it, so that the concrete can adhere to it more tightly. A rebar is called rebar because it is a reinforcing bar, and the common usage name developed.
Concrete and Rebar
Concrete has great compression strength, but has little tensile strength, so rebar is used within concrete to carry its tensile loads. This is the reason rebar and concrete are so often married together in construction usage. Rebar is set both horizontally and vertically in concrete, in walls and floors.
The other structural reason rebar and concrete are used together is that concrete and rebar have similar coefficients when it comes to thermal expansion. There is a minimal amount of stress between the rebar and the concrete as they expand and contract.