Universal Daytime Running Light A running light, also known as a daytime running light (DRL), is a vehicle light designed to enhance visibility during the day and improve safety by making a vehicle more noticeable to other drivers. Unlike standard headlights, which are typically used in low-light conditions, running lights are meant to be used during the daytime when the vehicle is moving. These lights are often integrated into the vehicle's design and provide a constant, non-blinking illumination.