A head Light or Head lamp is a lamp which is usually attached to the front of a vehicle, such as a car, a bus, a bike, etc. Its main purpose is, to provide light in front of the vehicle during night time, or during those times when it is dark and the visibility is very low. During night time, or dark conditions the headlight or head lamp of a car illuminates the road ahead and helps the driver to see ahead, thereby reducing the risk of any possible accidents.

A head lamp can be used in a bicycle too, by mounting it along the handle using it with a small battery. Aeroplanes and Trains also have their own Head lamps.

Head lamps are available in the market in various shapes and designs. Earlier they were perfectly round, as that was the easiest and the most convenient to make. Round head lamps were also very good reflectors of light.

Earlier, rectangular head lamps were also introduced once, but were not a huge success, as they were not very stylish and up to the public's demand.

Then the usual Round or oval head lamps again gained momentum and are being used till now.

The head lights being used today, are electrically operated and exist in pairs in a vehicle. One is on the right corner of the vehicle and the other is on the left.

Head light system in developed vehicles, produces a high and low beam for various purposes. The high beam is a beam of light which helps the user to see long ahead, while a low beam helps the user to see just around the car. High beam is required in long roads like highways, where as low beams are required during snowfall or foggy nights.

Low beams are also used when one needs to travel on a busy road, as they do not produce a glare, and hence does not disturbs other drivers coming from the opposite side of the road. Where as a high beam is preferred when one is travelling alone on a road as it produces a glare in other drivers' eyes.

The headlights are based on the principle of Reflector optics or lens optics. The light beam from the source inside the bulb, is reflected again and again inside the Head Lamp, in order to produce a large beam of parallel rays emanating from the main source. Hence the reflector optics increases the intensity of the beam of light for the same small source of light.

The light sources to be used in the head light can be any. For example, one can use Tungsten Light source, or a halogen light source or HID light sources, depending upon his budget.

Thus, head lights are an important piece of a vehicle. They are required in order to have visibility while driving during dark conditions and help to avoid accidents.