HID

HID, or high-intensity discharge light bulbs and lamps, are a family of gas-discharge arc lamps which create light by sending an electrical discharge between two electrodes and through a plasma, or ionized gas. An additional gas is generally used, and this gas serves as an easy way to classify the major types of HID lamps: Mercury, sodium, and metal halide.

These lamps are known for their high efficiency at turning electricity into light and their long rated life. HID lamps require a ballast in order to generate the initial surge of electricity needed to start them and to regulate their power during normal operation.