What is a marker light?

A marker light is a small, auxiliary light found on the exterior of a vehicle or aircraft. Its purpose is to indicate the position of the vehicle or aircraft in low-light or nighttime conditions. Marker lights can be found on the front, sides, and rear of vehicles and aircraft, and are typically colored red, green, or amber. They are often mounted in a recessed housing to protect them from damage and can be either illuminated continuously or flashing. Marker lights are an important safety feature and are required by law on all vehicles and aircraft.