A headlamp is a lamp connected to the entrance of a automobile to illuminate the highway ahead. Headlamps are additionally usually referred to as headlights, but in probably the most exact utilization, headlamp is the time period for the machine itself and headlight is the term for LED bulbs for home the beam of mild produced and distributed by the gadget. Headlamp efficiency has steadily improved all through the car age, spurred by the good disparity between daytime and energy-efficient bulbs nighttime site visitors fatalities: the US National Freeway Site visitors Security Administration states that almost half of all visitors-related fatalities occur at the hours of darkness, despite solely 25% of traffic travelling throughout darkness. Different automobiles, resembling trains and aircraft, energy-efficient bulbs are required to have headlamps. Bicycle headlamps are sometimes used on bicycles, and dimmable LED bulbs 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 journey at speed.

The earliest lights used candles as the most typical type of fuel. The earliest headlamps, fuelled by combustible gasoline comparable to acetylene fuel or oil, energy-efficient bulbs operated from the late 1880s. Acetylene gasoline lamps had been in style in 1900s as a result of the flame is resistant to wind and rain. Thick concave mirrors combined with magnifying lenses projected the acetylene flame mild. Quite a lot of automobile manufacturers supplied Prest-O-Lite calcium carbide acetylene fuel generator EcoLight cylinder with gas feed pipes for lights as customary tools for 1904 cars. The first electric headlamps were launched in 1898 on the Columbia Electric Car from the Electric Vehicle Company of Hartford, EcoLight dimmable Connecticut, and were elective. Two elements limited the widespread use of electric headlamps: the quick life of filaments in the cruel automotive setting, and the difficulty of producing dynamos small enough, yet highly effective sufficient to supply ample present. Peerless made electric headlamps normal in 1908. A Birmingham, England firm referred to as Pockley Vehicle Electric Lighting Syndicate marketed the world's first electric automobile-lights as a whole set in 1908, energy-efficient bulbs which consisted of headlamps, sidelamps, energy-efficient bulbs and tail lights that have been powered by an eight-volt battery.

In 1912 Cadillac built-in their automobile's Delco electrical ignition and lighting system, forming the trendy automobile electrical system. The Guide Lamp Company introduced "dipping" (low-beam) headlamps in 1915, however the 1917 Cadillac system allowed the light to be dipped using a lever inside the automotive reasonably than requiring the driver to stop and get out. The 1924 Bilux bulb was the primary modern unit, having the light for both low (dipped) and high (major) beams of a headlamp emitting from a single bulb. An identical design was launched in 1925 by Information Lamp referred to as the "Duplo". In 1927 the foot-operated dimmer swap or dip change was introduced and turned commonplace 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 known as "country passing", "nation driving" and "metropolis driving". The 1934 Nash also used a three-beam system, though in this case with bulbs of the conventional two-filament kind, and the intermediate beam mixed low beam on the driver's side with excessive beam on the passenger's aspect, so as to maximise the view of the roadside whereas minimizing glare towards oncoming traffic.

1952 "Autronic Eye" system automated the selection of high and low beams. Directional lighting, using a swap and electromagnetically shifted reflector to illuminate the curbside solely, was launched in the rare, one-12 months-only 1935 Tatra. Steering-linked lighting was featured on the 1947 Tucker Torpedo's center-mounted headlight and was later popularized by the Citroën DS. This made it doable to show the sunshine within the path of travel when the steering wheel turned. The standardized 7-inch (178 mm) spherical sealed-beam headlamp, one per side, was required for all vehicles bought within the United States from 1940, just about freezing usable lighting expertise in place until the 1970s for Americans. In 1957 the regulation modified to allow smaller 5.75-inch (146 mm) spherical sealed beams, two per aspect of the car, and in 1974 rectangular sealed beams had been permitted as properly. Britain, Australia, and another Commonwealth international locations, in addition to Japan and Sweden, EcoLight solutions also made intensive use of 7-inch sealed beams, although they were not mandated as they have been in the United States.