Traffic lights are important devices used to control the flow of vehicles and pedestrians at intersections. They use three colors: red, yellow, and green. The red light means "stop," the green light means "go," and the yellow light warns drivers that the light is about to change. This system helps prevent accidents and keeps everyone safe on the road. When a traffic light changes, it helps organize the movement of cars and people. For example, when the light turns green, cars can move forward while pedestrians wait. This orderly system is crucial for busy places like cities, where many vehicles and people are constantly on the move.