A car battery is like a big power pack that helps your car start and run. Inside the battery, there are many small plates that are made of lead. These plates hold the electricity that the car needs to run.
When you turn the key in the car, the electricity from the battery flows through wires to the engine, which makes the car start moving. The battery also provides power to lights, radio and other electronics in the car.
To make sure the battery stays charged and can start the car, the alternator, which is like a little power plant in the car, recharges the battery while the car is running. This way, the next time you want to start the car, the battery will have enough power to make it go.