A mezzanine is an intermediate floor in a building that is placed halfway up the wall on a floor which has a ceiling at least twice as high as a floor with minimum height. It is an additional floor that is installed between the ceiling and the ground floor to provide extra space for storage, assembly operations, or office space and makes use of unused vertical space. Mezzanines may serve a wide variety of functions, and they are often used in industrial operations such as warehousing, distribution, or manufacturing. They can be made of steel, wood, concrete, or other materials. Mezzanine floors are typically free-standing structures that are designed specifically to match the space and capacity needs of a given facility. They are usually constructed of three main materials: steel, aluminum, and fiberglass. Mezzanines can be disassembled, stored, moved, and installed much like a piece of equipment or machinery.