Cast In Situ refers to a construction technique where concrete is poured and set directly at the construction site, rather than being pre-cast in a factory. This method allows for greater flexibility in design and can accommodate complex shapes and sizes that may be difficult to achieve with pre-cast elements. This technique is commonly used in various structures, including buildings, bridges, and foundations. By casting concrete on-site, builders can ensure that the material is tailored to the specific conditions and requirements of the project, leading to improved structural integrity and durability.