Lights are significant because they allow you to see your surroundings, give others a way to see you, and give other drivers indications of your future actions. Cars are required to have certain lighting fixtures, and these generally have luminosity regulations. Make sure that your vehicle has these fixtures in place and that they are fully functioning.
Vehicles must be equipped with low-beam as well as high-beam headlights. Low-beams must be turned on when it gets dark or in any moment of low visibility due to bad weather. Most states (e.g.,Alaska, Michigan, Nevada, Texas, Utah) require that lights must be turned on from one-half hour after sunset until one-half hour before sunrise. Other states, (e.g., Arizona, Virginia) require that lights are turned on from sunset to sunrise. Consult your state's Drivers Handbook for details.
Some states (e.g., California, Connecticut, Delaware) require by law that if you turn on your wipers you must also turn on your lights.
High-beams are also located at the front of your vehicle and have a higher luminosity that covers greater distance. High-beams are to be used in times of very low visibility. However, you are not to use high-beams in fog, for they will only reflect the dampened air and blind other drivers.
High-beams are to be turned off when another vehicle is in front of you or approaching on the opposite side of the road. Most of the states require that you switch to low-beams 500 ft. or more from oncoming vehicles. Consult your state's Drivers Handbook for details. The switch for headlights varies between vehicles. Consult your car's owner manual to make sure you know exactly how to turn your headlights on.
Each vehicle must also have taillights and brake lights. Most of the states require that the taillights be visible from 500 ft. Taillights are red and are located on the back of your vehicle. Brake lights light up when you hit brakes to signal the drivers behind you to stop.
Parking lights are located at the front and back of your vehicles; they are white or amber in the front and red on the back. All of them must be visible for 500 ft. It is never legal to drive with your parking lights on; they are only to be used during parking.