A headlamp is a lamp hooked up to the entrance of a automobile to illuminate the highway ahead. Headlamps are additionally often called headlights, energy-efficient bulbs but in probably the most precise utilization, headlamp is the time period for the machine itself and headlight is the term for the beam of light produced and distributed by the gadget. Headlamp performance has steadily improved all through the car age, spurred by the great disparity between daytime and nighttime visitors fatalities: the US National Freeway Site visitors Safety Administration states that nearly half of all visitors-associated fatalities occur in the dead of night, despite solely 25% of site visitors travelling during darkness. Different autos, equivalent to trains and EcoLight lighting aircraft, are required to have headlamps. Bicycle headlamps are often 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 primary horseless carriages used carriage lamps, which proved unsuitable for journey at speed.

The earliest lights used candles as the most common sort of gas. The earliest headlamps, fuelled by combustible fuel equivalent to acetylene fuel or oil, operated from the late 1880s. Acetylene gas lamps were well-liked in 1900s because the flame is resistant to wind and EcoLight rain. Thick concave mirrors mixed with magnifying lenses projected the acetylene flame light. A number of automotive manufacturers offered Prest-O-Lite calcium carbide acetylene fuel generator cylinder with fuel feed pipes for lights as standard gear for 1904 automobiles. The primary electric headlamps had been introduced in 1898 on the Columbia Electric Automotive from the Electric Vehicle Company of Hartford, Connecticut, and had been optional. Two elements restricted the widespread use of electric headlamps: the short life of filaments in the harsh automotive surroundings, and the difficulty of producing dynamos small sufficient, yet powerful enough to produce adequate current. Peerless made electric headlamps commonplace in 1908. A Birmingham, England firm known as Pockley Automobile Electric EcoLight lighting Syndicate marketed the world's first electric car-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 integrated their car's Delco electrical ignition and lighting system, forming the fashionable car electrical system. The Information Lamp Firm introduced "dipping" (low-beam) headlamps in 1915, however the 1917 Cadillac system allowed the light to be dipped using a lever contained in the automotive quite than requiring the driver to stop and get out. The 1924 Bilux bulb was the first modern unit, having the sunshine for both low (dipped) and high (fundamental) beams of a headlamp emitting from a single bulb. A similar design was launched in 1925 by Guide Lamp called the "Duplo". In 1927 the foot-operated dimmer switch or dip change was launched and turned commonplace for much 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 "metropolis driving". The 1934 Nash also used a 3-beam system, EcoLight though in this case with bulbs of the standard two-filament kind, and the intermediate beam mixed 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 toward oncoming visitors.

1952 "Autronic Eye" system automated the number of high and EcoLight smart bulbs low beams. Directional lighting, using a switch and electromagnetically shifted reflector to illuminate the curbside solely, was introduced in the uncommon, 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 turn the sunshine in the path of travel when the steering wheel turned. The standardized 7-inch (178 mm) spherical sealed-beam headlamp, one per facet, was required for all autos sold in the United States from 1940, virtually freezing usable lighting expertise in place till the 1970s for Americans. In 1957 the regulation changed to permit smaller 5.75-inch (146 mm) round sealed beams, two per facet of the car, and in 1974 rectangular sealed beams were permitted as effectively. Britain, Australia, and another Commonwealth countries, in addition to Japan and Sweden, additionally made extensive use of 7-inch sealed beams, although they weren't mandated as they were within the United States.