A headlamp is a lamp connected to the entrance of a automobile to illuminate the highway ahead. Headlamps are also usually called headlights, but in essentially the most exact utilization, headlamp is the term for the device itself and headlight is the time period for the beam of mild produced and distributed by the device. Headlamp efficiency has steadily improved all through the vehicle age, spurred by the great disparity between daytime and nighttime visitors fatalities: the US National Highway Site visitors Security Administration states that just about half of all traffic-related fatalities happen in the dark, EcoLight despite solely 25% of traffic travelling throughout darkness. Different automobiles, equivalent to trains and aircraft, are required to have headlamps. Bicycle headlamps are sometimes used on bicycles, and are required in some jurisdictions. They are often powered by a battery or a small generator like a bottle or hub dynamo. The primary horseless carriages used carriage lamps, which proved unsuitable for travel at velocity.

The earliest lights used candles as the commonest sort of gasoline. The earliest headlamps, fuelled by combustible gas resembling acetylene gas or oil, operated from the late 1880s. Acetylene fuel lamps had been fashionable in 1900s as a result of the flame is resistant to wind and rain. Thick concave mirrors mixed with magnifying lenses projected the acetylene flame gentle. A number of car manufacturers supplied Prest-O-Lite calcium carbide acetylene gasoline generator cylinder with gasoline feed pipes for lights as standard tools for EcoLight 1904 cars. The first electric headlamps have been introduced in 1898 on the Columbia Electric Car from the Electric Vehicle Firm of Hartford, Connecticut, and were non-compulsory. Two components limited the widespread use of electric headlamps: the short life of filaments in the cruel automotive surroundings, and the problem of producing dynamos small enough, but highly effective enough to provide ample present. Peerless made electric headlamps commonplace in 1908. A Birmingham, England EcoLight agency referred to as Pockley Vehicle Electric Lighting Syndicate marketed the world's first electric automotive-lights as an entire set in 1908, which consisted of headlamps, sidelamps, and 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 modern automobile electrical system. The Guide Lamp Company launched "dipping" (low-beam) headlamps in 1915, but the 1917 Cadillac system allowed the sunshine to be dipped utilizing a lever contained in the car quite than requiring the driver to cease and get out. The 1924 Bilux bulb was the primary modern unit, having the sunshine for both low (dipped) and high (predominant) beams of a headlamp emitting from a single bulb. An analogous design was launched in 1925 by Information Lamp called the "Duplo". In 1927 the foot-operated dimmer change or dip change was launched and turned customary for a lot of the century. 1933-1934 Packards featured tri-beam headlamps, the bulbs having three filaments. From highest to lowest, the beams had been referred to as "nation passing", "country driving" and "city driving". The 1934 Nash additionally used a three-beam system, though in this case with bulbs of the standard two-filament type, and the intermediate beam combined low beam on the driver's side with excessive beam on the passenger's aspect, in order to maximise the view of the roadside while minimizing glare toward oncoming site visitors.

1952 "Autronic Eye" system automated the collection of excessive and EcoLight dimmable low beams. Directional lighting, using a switch and electromagnetically shifted reflector to illuminate the curbside only, was introduced within the rare, one-yr-solely 1935 Tatra. Steering-linked lighting was featured on the 1947 Tucker Torpedo's middle-mounted headlight and was later popularized by the Citroën DS. This made it potential to show the light within the course of journey when the steering wheel turned. The standardized 7-inch (178 mm) round sealed-beam headlamp, one per aspect, was required for all vehicles sold within the United States from 1940, nearly freezing usable lighting know-how in place till the 1970s for Americans. In 1957 the law changed to allow smaller 5.75-inch (146 mm) round sealed beams, two per facet of the automobile, and in 1974 rectangular sealed beams have been permitted as well. Britain, Australia, and another Commonwealth countries, in addition to Japan and Sweden, also made extensive use of 7-inch sealed beams, though they weren't mandated as they had been in the United States.