Pilot lights are electrical indicators that show when electrical power is available or when a machine is operating. They typically use LEDs to provide the light, but incandescent bulbs may be used on older devices.
Pilot lights come in wide variety of sizes, shapes, materials and colors, and so can be built to meet specific requirements.
Generally, pilot lights are assembled to fill two primary requirements: lens color, to differentiate between different status conditions on a machine or panel (green for on, red for off, for example), and protection rating for assured operation in a wide variety of environments. Other properties like terminal type, push-to-test, lamp voltage, lens shape and more can be chosen as well.