How does prepay gas work when filling up at the gas station?

When you prepay for gas at the gas station, you pay a certain amount of money before you start pumping gas into your vehicle. The gas station attendant or the pump itself will authorize the pump to dispense gas up to the amount you paid. Once you reach that amount, the pump will stop automatically, and you can choose to pay more if you need to fill up further. This system helps prevent customers from driving off without paying for the gas they have pumped.