The color that signifies danger in traffic lights is red. Red lights indicate that drivers must stop and not proceed when the light is illuminated. This color was chosen for its visibility and strong psychological association with alarm and caution. The use of red as a warning signal extends beyond traffic lights to road signs and emergency vehicles, where it alerts people to potential hazards or urgent situations. Traffic signals are standardized in many countries, promoting safety by ensuring that drivers understand the meaning of different signals internationally. Understanding this system is vital for effective road safety and traffic regulation.