What does AUTO mean on car lights?

[StJocelyn]

AUTO stands for automatic, and AUTO on car lights refers to the automatic control of turning the lights on and off based on environmental conditions. Here is a detailed explanation: 1. When the car light is set to this position, the lights will not turn on during the day, but they will automatically turn on at night. In tunnels, cloudy weather, or any dimly lit areas, the lights will automatically turn on; once you exit the tunnel or when lighting conditions improve, the lights will turn off accordingly. 2. The principle is: sensors such as photoresistors (installed behind the rearview mirror, etc.) send electronic signals to the ECU (Electronic Control Unit, similar to a computer's CPU, both meaning roughly the same thing), informing the ECU whether to turn the headlights on or off or switch between high and low beams. The ECU then controls the headlight switch and the change between high and low beams. 3. Smart headlights not only control the turning on and off of the lights based on environmental conditions but can also switch between high and low beams and adjust the lighting distance of the headlights.