Modular Prefabricated Buildings, often referred to as modular site cabins or portable buildings, are structures constructed from pre-engineered, factory-built sections or modules. These modules are manufactured off-site in a controlled environment, then transported and quickly assembled on-site using bolted connections.

They are designed for rapid deployment, reusability, and flexibility, serving as temporary, semi-permanent, or even permanent facilities. Common materials include a steel frame with insulated composite panels (often steel-faced with a foam or rock wool core) for walls, roof, and floor.