H=High I=Intensity D=Discharge

“High Intensity Discharge” is shortened as “HID”.

Using the principle of arch discharge, High Intensity Discharge produces arc light by lighting two electrodes, burning Xenon, iodide and such inertia gases contained inside a bulb, superseding the conventional lighting by burning tungsten filaments. 

The term HID originated from hypertension discharge.  Since Xenon is filled inside the bulb, HID lamp is also referred to as a Xenon lamp.  In its early stages, HID lighting technology has applied to the lighting on sports fields.  HID headlamps are essential standard equipment on leading-brand cars, such as Benz, BMW, Lexus, Audi, etc. 

It is safe to say that in the future, HID headlamps will be universally used on all vehicles.  In recent years, some cars have used HID headlamps to replace the conventional halogen lamps.