- Definition: 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. These lamps are known for their high efficiency of 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.
- Example: Outdoor lighting in parking lots generally use H.I.D. lamps but could be much more energy efficient with the use of LEDs.
Reference: https://bulbs.com/learning/hid.aspx