Roller shutter doors are a form of modern security to provide a solid barrier in openings such as windows, doors, shop fronts and access to premises. Known variously as roller shutters and roller doors because of the way they roll up onto an axle when they are opened, the correct name is a sectional overhead door.
The shutters are made up of horizontal slats, sometimes constructed as bars or web systems, which are all hinged together to form a single sheet barrier. The door is then closed by rotating the top axle to wind up the door into a compact cylinder, or feeding the sections out in reverse to close the opening being protected. The doors can be operated manually with a drive chain, or for larger heavier doors be driven by a motor. While the main purpose of this type of door is security to prevent theft and vandalism, they also serve as an excellent weather barrier, protecting premises from the wind and rain.