A "back-up light," also known as a "reverse light" or "backup lamp," is a lighting fixture on a vehicle that illuminates when the vehicle's transmission is shifted into the "reverse" gear. The primary purpose of a back-up light is to provide additional visibility to the driver when backing up, especially during low-light conditions or at night. These lights help indicate the vehicle's intention to reverse and also alert pedestrians and other drivers of the vehicle's movement.