A type of lamp that uses a similar principle to fluorescent lighting but produces large amounts of light and consequently consumes large amounts of energy. They are usually manufactured in a form that resembles either a small tube or an odd-looking lightbulb. Common varieties of HID lamps include mercury, metal halide and sodium, and these lamps may produce light by exciting special gases (the principle behind fluorescent lamps) and/or heating of a metal filament to the point where it gives off light (the principle behind incandescent lamps). Wattages can range from a few hundred to several thousand watts per lamp. These types of lamps are typically used for streetlights, "stadium lighting" and greenhouse lighting.

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