Headlamp is a lamp, usually attached to the front of a vehicle such as a car, can also be mounted on a bicycle (with a battery or small electrical generator), and most other vehicles from airplanes to trains tend to have headlamps of their own, with the purpose of illuminating the road ahead during periods of low visibility, such as night or precipitation. While it is common for the term headlight to be used interchangeably in informal discussion, headlamp is the technically correct term for the device itself, while headlight properly refers to the beam of light produced and distributed by the device.
On the other hand, head-lamp is a simply flashlight lamp worn on a comfortable headband. Since headlamps leave both handsfree, reviews recommend them for household power outages as well as for remodeling, auto repair and construction tasks.Headlamps are also useful, of course, for all kinds of outdoor sports - hiking, running, cycling, climbing and more.Reviewers now recommend LED headlamps as the best type, since LED technology can now provide bright light with long battery life. LED bulbs are also virtually unbreakable and last 50, 000 to 100, 000 hours - compared with about 40 hours for an inncandescent headlamp bulb.
The best headlamp based on detailed tests.Specific ratings cover eleven factors, including comfort and value. REI.com can be refered to Choose a suitable headlamp. The REI reviews are especially useful because they include staff measurements of the light output of each headlamp.But for some purposes, other factors are more important -- such as weight, comfort and beam width. Both objective tests and owner-written reviews show that specifications don't tell the whole story; some headlamps perform better than others, and battery life seems to really separate models.For comfort, ease of use and value, Backpacking Light gives top ranking to the waterproof, which carries a lifetime warranty.
Headlamps for general use.For relatively close-up task lighting - for household use during power outages, reading in bed, changing a car tire or battery, or for campsite use - reviews recommend headlamps with wide flood beams. This type of headlamp doesn't provide red light for night vision, and they don't throw light far enough ahead to be good for running or hiking on challenging trails. Most headlamps provide a strobe mode. This flashing light can be seen for long distances, which is useful for emergencies. Headlamp reviews note that the brightest available light isn't always the most useful. Lower light levels are better for reading (especially for reading in bed or in a tent without disturbing a partner), and also make batteries last longer. So the best headlamps have adjustable brightness levels.
References
http://www.consumersearch.com/headlamps/review
http://en.wikipedia.org/wiki/Headlamp#History_of_automotive_headlamps
http://www.danielsternlighting.com/tech/lights/codes/codes.html#Dip