Most people refer to prefabricated factory or off-site construction when they specify light gauge steel frame structures. They are pre-engineered and arrive on-site in ready to assemble built format. All components are labeled drilled, punched, and ready to bolt or screw together.
Each unit is delivered with a clear panel, floor and roof plan and can be assembled and erected in a very short period of time. As much of the build as possible is prefabricated within the factory environment. Which reduces the environmental impact.
These units can be built on a variety of different foundation types and the cladding possibilities are endless. Panelised fabrication system allows high-speed manufacture of transportable and modular houses in factory environments. A popular market is bathroom pods.