Fabrication is a process of manufacturing that often involves cutting, shaping and welding of steel or iron. The end result is creation of structures that fit in a building being constructed or fit in with completed building as parts of ancillaries. The examples of former are used in making prefabricated structures that accord a sound foundation to a building. The latter acts as parts of building like staircase, windows, doors, gates, grills and so on. Metal fabricators use light weight high tensile structural sheets in many forms for the output.
But fabrication is not as simple as is spelled out here. A large number of processes are involved under expertise and sophisticated machinery to create these products that are eventually assembled into the building. This takes place in a well equipped fab shop laced with experts and skilled technicians in order to give a desired shape pertaining to a quality as desired.
The prefabricated parts or building blocks are transported to the site and then erected under an installation process. Hence the fab shops specialize as fabricators as well installers during the construction process.