Runway edge lights are used to help pilots land safely during periods of darkness or low visibility. They outline the edges of runways in white or yellow lights. Yellow indicates that there is less than 2,000 feet of runway left.
Threshold lights are used to ensure that pilots of both landing and departing aircraft know exactly where the runway begins and ends, respectively. This helps to prevent crashes due to planes overshooting or undershooting the runway.
Threshold lights change color, depending on the situation. If a plane is landing, the lights are green to indicate the beginning of the runway. If a plane is departing, the lights are red to indicate the end of the runway.
