A start-stop system is a technology used in vehicles to improve fuel efficiency and reduce emissions. It automatically turns off the engine when the vehicle is stationary, such as at traffic lights or in heavy traffic, and restarts it when the driver releases the brake or presses the accelerator. This helps save fuel by preventing unnecessary idling. This system is commonly found in modern cars and is often integrated with hybrid or electric vehicle technologies. By minimizing engine run time, the start-stop system contributes to lower carbon emissions and can enhance overall vehicle efficiency, making it an important feature in eco-friendly driving.