Mirror systems enable the driver to observe the traffic behind and to the side and thus primarily serve driving safety. A basic distinction must be made between interior mirrors and exterior mirrors. Interior mirrors are individually adjustable to the driver and allow the driver to look through the rear window. The dimming function is either manual or automatic via integrated LDR sensors and electrochromic glass. Other comfort features include rain sensors, automatic lights or memory functions for the mirror position. Exterior mirrors, on the other hand, allow the driver to look along the side of the vehicle to the rear. Reflective properties (planar, convex or aspherical) allow the angle of vision to be widened. Modern mirror systems are mechanically or electrically adjustable on both sides and can be adapted to the driver's needs. Mechanical adjustment is achieved via three Bowden cables, while electrical adjustment is done via the driver's door controls. Depending on the model, modern mirror systems have additional functions: Direction indicator, electric folding and unfolding, mirror glass heating, integrated blind spot monitoring or cameras. Mirror systems are used by OEM on two-wheelers, passenger cars as well as commercial, special and rail vehicles. Moving trailers may require additional side mirrors due to the larger vehicle width. An extension of the visible area is possible, for example, via rear-view cameras.