High Intensity Discharge (HID) lights have a glass chamber of gas that replaces the filament of traditional halogen light bulbs. The gas is ignited with an approximately 23,000 volt charge and stays illuminated by a constant 12v source that is provided by a ballast which is connected directly to your battery.

Cheap xenon-filled halogen bulbs do not use the same technology and are tinted blue to give off a white light. They still have a filament and produce less light output then standard halogen bulbs of the same wattage.