Car window tinting businesses apply a tinted film to the glass of cars and other vehicles. The film is usually fitted to the inside of the windows and is available in different shades and finishes. Customers may choose tinting to reduce glare, limit sunlight and ultraviolet radiation entering the vehicle, increase privacy in the rear passenger area, or change the appearance of the glass. Some films are designed to reduce heat or help hold fragments together if glass breaks. Services commonly include discussing suitable films, preparing the glass, cutting film to fit each window and applying it with care to minimise bubbles and creases. Businesses may also remove or replace old, damaged or poorly fitted tint. Tinting must comply with UK rules on how much light passes through the windscreen and front side windows; darker films are generally restricted to rear windows.