Vehicle traffic signals are lights, mechanical flags, audio speakers, or other forms of signage which display or broadcast dynamically changing commands to road traffic (especially cars, trucks, motorbikes, etc.). The most common form is a stack of 3 differently colored lights signaling vehicles to go, proceed with caution, and stop.

The commands address road vehicles. Their display can use changing lights, moving mechanical parts, or sound; a three-light stack is a common arrangement.

Foot traffic signals address pedestrians, while tram traffic signals address light rail. Signals for these different users can share an intersection.