In order to compare types of lighting, a basic understanding of how each works is necessary. A standard incandescent light consists of a tungsten filament inside a gas-filled bulb. When the bulb is turned on, a current is sent through the filament. Tungsten has a high electrical resistance, so the current generates heat, which then produces light. The gas inside the bulb slows the evaporation of the tungsten filament, but eventually the heat will cause the filament to decay enough to break, causing the light bulb to go out.

HID lights have a capsule of gas instead of the tungsten filament. The gas is actually used to produce light instead of simply slowing the decay of the bulb. Two electrodes are positioned close together and hermetically sealed inside the gas capsule. The electrodes are wired to a ballast containing a circuit board with several high current capacitors, transistors, and resistors. The ballast acts as the light's control center, igniting the light and then regulating its power flow.

When the ballast ignites, it takes in a small amount of power and creates an intense charge of electricity across the electrodes. This electrical charge excites the gas molecules inside the bulb and causes them to discharge photon particles, producing light. Because the light is based on this gas discharge, HID lights only produce about 5% of their total output at ignition and can require up to 30 seconds to warm up to full power. If the light is turned off, it must cool to a certain temperature before it can be re-ignited.

This process creates several significant advantages over a standard light bulb. Because heat not a necessary component of light production in HID lights, they are able to produce the same or even more light at a much cooler temperature. HID lights are also far more efficient because the electrical current is only the catalyst for the gas to discharge its light particles, not the primary source of heat and light. The ballast regulates a constant flow of power only to keep the gas molecules excited, while a standard light requires a constant intense electrical current to keep the filament hot. HID bulbs will last longer than standard bulbs because of the rapid decay of the tungsten filament and will also produce more light toward the end of its life.

In addition to being more efficient, HID lights also produce brighter and more intense light because the entire capsule of gas is used instead of just a small filament in the middle of the bulb. This also means that the light will be distributed more evenly than with a standard bulb. This advantage in light quality is a major reason why HID systems are preferable for automotive and gardening lights. Motorists are able to see much more with HID headlights than with standard halogen headlights. In fact, many car manufacturers are including HID lights as part of their standard package instead of making them a luxury upgrade.

This process creates several significant advantages over a standard light bulb. Because heat not a necessary component of light production in HID lights, they are able to produce the same or even more light at a much cooler temperature. HID lights are also far more efficient because the electrical current is only the catalyst for the gas to discharge its light particles, not the primary source of heat and light. The ballast regulates a constant flow of power only to keep the gas molecules excited, while a standard light requires a constant intense electrical current to keep the filament hot. HID bulbs will last longer than standard bulbs because of the rapid decay of the tungsten filament and will also produce more light toward the end of its life.

In addition to being more efficient, HID lights also produce brighter and more intense light because the entire capsule of gas is used instead of just a small filament in the middle of the bulb. This also means that the light will be distributed more evenly than with a standard bulb. This advantage in light quality is a major reason why HID systems are preferable for automotive and gardening lights. Motorists are able to see much more with HID headlights than with standard halogen headlights. In fact, many car manufacturers are including HID lights as part of their standard package instead of making them a luxury upgrade.