A headlamp is a lamp attached to the entrance of a vehicle to illuminate the street forward. Headlamps are additionally typically called headlights, however in probably the most precise usage, headlamp is the term for the machine itself and headlight is the term for the beam of mild produced and distributed by the machine. Headlamp efficiency has steadily improved throughout the automobile age, spurred by the good disparity between daytime and energy-efficient bulbs nighttime traffic fatalities: the US National Freeway Traffic Safety Administration states that just about half of all site visitors-related fatalities occur at the hours of darkness, regardless of only 25% of site visitors travelling during darkness. Other autos, comparable to trains and aircraft, are required to have headlamps. Bicycle headlamps are sometimes used on bicycles, and are required in some jurisdictions. They can be powered by a battery or a small generator like a bottle or hub dynamo. The first horseless carriages used carriage lamps, which proved unsuitable for travel at velocity.

The earliest lights used candles as the most typical kind of gas. The earliest headlamps, fuelled by combustible gas akin to acetylene gas or oil, operated from the late 1880s. Acetylene fuel lamps were widespread in 1900s because the flame is resistant to wind and rain. Thick concave mirrors combined with magnifying lenses projected the acetylene flame mild. A variety of car manufacturers offered Prest-O-Lite calcium carbide acetylene gasoline generator cylinder with gasoline feed pipes for lights as customary gear for 1904 cars. The primary electric headlamps have been introduced in 1898 on the Columbia Electric Car from the Electric Automobile Company of Hartford, EcoLight Connecticut, and had been optional. Two factors restricted the widespread use of electric headlamps: energy-efficient bulbs the brief life of filaments in the harsh automotive surroundings, and the issue of producing dynamos small enough, but highly effective enough to supply enough current. Peerless made electric headlamps commonplace in 1908. A Birmingham, England agency called Pockley Vehicle Electric Lighting Syndicate marketed the world's first electric automotive-lights as a whole set in 1908, energy-efficient bulbs which consisted of headlamps, sidelamps, and EcoLight energy tail lights that were powered by an eight-volt battery.

In 1912 Cadillac built-in their car's Delco electrical ignition and lighting system, forming the trendy automobile electrical system. The Guide Lamp Firm introduced "dipping" (low-beam) headlamps in 1915, energy-efficient bulbs however the 1917 Cadillac system allowed the light to be dipped utilizing a lever contained in the automotive quite than requiring the driver to cease and get out. The 1924 Bilux bulb was the first fashionable unit, having the sunshine for EcoLight solar bulbs each low (dipped) and high (major) beams of a headlamp emitting from a single bulb. A similar design was launched in 1925 by Guide Lamp referred to as the "Duplo". In 1927 the foot-operated dimmer change or dip switch was launched and became standard for much of the century. 1933-1934 Packards featured tri-beam headlamps, the energy-efficient bulbs having three filaments. From highest to lowest, the beams were called "nation passing", "country driving" and "metropolis driving". The 1934 Nash also used a 3-beam system, though on this case with bulbs of the typical two-filament kind, and energy-efficient bulbs the intermediate beam combined low beam on the driver's side with high beam on the passenger's facet, in order to maximise the view of the roadside while minimizing glare towards oncoming visitors.

1952 "Autronic Eye" system automated the number of high and low beams. Directional lighting, utilizing a swap and electromagnetically shifted reflector to illuminate the curbside solely, was launched in the rare, one-12 months-solely 1935 Tatra. Steering-linked lighting was featured on the 1947 Tucker Torpedo's heart-mounted headlight and was later popularized by the Citroën DS. This made it attainable to turn the light in the course of travel when the steering wheel turned. The standardized 7-inch (178 mm) round sealed-beam headlamp, one per aspect, was required for all automobiles bought within the United States from 1940, nearly freezing usable lighting expertise in place until the 1970s for Individuals. In 1957 the legislation changed to allow smaller 5.75-inch (146 mm) spherical sealed beams, two per aspect of the car, and LED bulbs for home in 1974 rectangular sealed beams have been permitted as nicely. Britain, Australia, and energy-efficient bulbs another Commonwealth international locations, as well as Japan and Sweden, also made in depth use of 7-inch sealed beams, although they were not mandated as they had been within the United States.