1. Fuel must be mixed with air in order to burn. It is mixed in the carburetor, to produce a vapor. This vapor is drawn through one-way holes called valves, to the top of the cylinders. An engine bay has 4, 5, 6, 8, or more cylinders. If the engine uses a fuel injection system, the fuel is injected into a chamber at the end of each cylinder where it mixes with the air to form a vapor.

2. At the top of each cylinder there is a spark plug, getting current from the distributor. The top of the spark plug has two stiff wires with a little space between them. When the current jumps across this space it makes a hot spark which sets fire to the gasoline vapor in the cylinder.

3. As the vapor explodes, it expands, pushing the piston down. The piston is attached to a rod, which is attached to the crankshaft.

4. As the rods are pushed down one after the other, they push the crankshaft around just the way your foot pushes the pedal of your bicycle around.

5. The crankshaft turns the gears in the transmission. The gears turn the drive shaft. The drive shaft turns the differential gears, which turn the wheels that move the car.