Traffic signals (traffic lights) are electronically controlled devices using colored lights (red, yellow/amber, green) to direct traffic flow at intersections and other locations. Signals improve safety and efficiency at high-volume intersections where stop signs would cause excessive delays. Modern signals use timing plans optimized for traffic patterns, with some systems coordinated across corridors to create 'green waves.' Pedestrian signals provide crossing phases and countdown timers. Advanced systems detect approaching vehicles and adjust timing dynamically. Signal installation decisions consider traffic volumes, collision history, pedestrian activity, and warrant criteria. Municipalities operate and maintain traffic signals on local roads while provinces manage highway signals. Signal maintenance includes lamp replacement, controller updates, and timing optimization.