In darkness or difficult lighting conditions headlights serve to illuminate the surrounding area. All lighting equipment on the exterior of a car requires technical approval. The most used headlight is the dipped beam. Full-beam headlights increase the illuminated area in the dark and where traffic density is low. Besides these, the only approved additional lights are fog lights. These may be switched on only in bad weather, for instance in fog, rain or snowfall. On the other hand, rear fog lamps may only be operated when visibility is less than 50 m. With rear fog lamps switched on, the top speed is limited by law to 50 km/h Technically speaking, the reversing lamps for passenger cars are only tail lamps. Headlights are always arranged in pairs on the car. Indicators at the front, back and sides as well as side lights (parking lights) and lighting for the rear registration plate complete the lighting equipment of a car.
