Reinforcement in concrete refers to the use of steel bars, wire, or fibers to strengthen the concrete. The purpose of reinforcement in concrete is to increase the tensile strength of the material and to improve its ability to resist cracking and other types of damage.

There are several reasons why reinforcement is used in concrete construction:

1. To increase the tensile strength of the concrete: Concrete is a strong material in compression, but it is relatively weak in tension. By adding reinforcement to the concrete, the tensile strength of the material can be increased, allowing it to resist forces that try to stretch or bend it.

2. To improve the durability of the concrete: Reinforcement can help to improve the durability of concrete by reducing the risk of cracking and other types of damage. This is especially important in structures that are subjected to extreme loads or environments, such as bridges, highways, and buildings in earthquake-prone areas.

3. To reduce the amount of concrete required: Because reinforcement can increase the tensile strength of the concrete, it may be possible to use less concrete in a structure while still maintaining its strength and stability. This can be an important consideration in situations where the cost or availability of concrete is a concern.