HID stands for High-Intensity Discharge. An HID lamp produces light from an electrical arc in a gas-filled discharge tube and requires control gear, often called a ballast. HID lamps can provide high light output but require warm-up and restrike time and are less compact and controllable than LEDs. HID technology has been used where powerful, efficient illumination was required, including vehicle and industrial applications. Its ballast creates the high voltage needed to start the arc and then regulates operation. Compared with LEDs, the warm-up behavior, larger control gear, switching limitations, and maintenance requirements can make HID less suitable for frequently controlled or compact installations.