High Density Lamps (HID Lamps) and auto bulbs are made for indoor gardening, particularly for plants that require high levels of direct sunlight in their natural habitat. HID lamps, made of specifically metal halide and high-pressure sodium are very useful for indoor gardening. HID lamps are also used for indoor aquaria, to produce tropical intensity sunlight. HID lamps makes much visible light per unit than the ordinary fluorescent and incandescent lamp. The reason being, HID lamps and auto bulbs are used as unnatural sunlight for plants and animals on places where sunlight comes out in rarity.
The largest market of HID manufacturer and auto bulb supplier are found in China. As China has been into producing many electronic items, these have been the most accepted in the market. HID lamps and auto bulbs are a type of electrical gas-discharge lamp which produces light by means of an electric arc between tungsten electrodes inside a translucent fused quartz. HID bulbs are used in cricket stadiums for floodlights, football stadiums, gymnasiums, warehouse, large public areas etc. Recently HID lamps have been used in large LCD and DLP televisions sets or projection displays which are used in meeting rooms and classrooms.