Traditional incandescent lamps work by driving current through a metal filament in the middle of the bulb. As a result, the filament heats up to the point where it begins to emit light, providing illumination. HID car xenon lights are different.

　　Rather than relying on a filament to provide light, HIDs drive an arc through a chamber filled with an inert gas (usually xenon), which is a basic description of what's going on inside one of the bulbs. Your ordinary HID lamp consists of three main parts: the ballast, the igniter, and the xenon bulb.

　　The moment the lights are turned on, the igniter element fires a high-voltage arc through the xenon bulb. Once you have established an arc inside the bulb, the ballast assembly takes over. Its job at this point is to drive a specific amount of voltage and current to keep the bulb burning at a consistent rate. Your ordinary HID light bulb not only contains an inert gas such as xenon but is also filled with salt that evaporates into a plasma state. From the moment you establish the plasma state, the bulb will increase its output until it reaches the default brightness. The next time you start your car, pay attention to what your headlights are doing, you can actually watch the entire process from the ignition phase to warm-up and final nominal brightness.

　　The benefits of HID lights are numerous and go well beyond cool aesthetics. Running HID in your car has a positive effect on your safety and night vision. On top of that, there are also issues of power efficiency and lamp life.