The color that represents danger in a traffic signal is red. Red is universally associated with caution and alertness in various contexts, particularly in traffic management. In traffic lights, red indicates that vehicles must stop, providing safety for both drivers and pedestrians. The choice of red has historical roots; it has been used as a warning color since ancient times due to its visibility from a distance. Its psychological impact elicits a sense of urgency and draws attention, making it an effective color for signaling danger or the need for immediate action.