In architecture, a mezzanine or entresol is an intermediate floor between main floors of a building, and therefore typically not counted among the overall floors of a building. Often, a mezzanine is low-ceilinged and projects in the form of a balcony. The mezzanine floor often projects itself from the walls and does not completely close the view of the ceiling from the floor immediately below. In short, a mezzanine floor and the floor below it share the same ceiling. Mezzanine floors are often located between the ground floor and the first floor but it is not unusual to have mezzanine floors in the upper floors of a building. In industrial applications, mezzanine floor systems are semi-permanent floor systems typically installed within buildings, built between two permanent original stories. These structures are usually free standing and in most cases can be dismantled and relocated. The mezzanine is often used in shops and similar spaces for storage of tools or materials. The high roof of the shop is ideal for a mezzanine, and offices can be put either below or above it. Mezzanines are frequently used in industrial operations such as warehousing, distribution or manufacturing. These facilities have high ceilings, allowing unused space to be utilized within the vertical cube. Industrial mezzanine structures are typically either structural, roll formed, rack-supported, or shelf-supported, allowing high density storage within the mezzanine structure.