The car engine can be intimidating; that big loud thing under the hood that makes the car move. The engine, or motor, is where all the power for the vehicle comes from. The engine works on the premise of controlled combustion. Literally thousands of mini explosions happen inside the motor per minute to help it create the power needed to move the vehicle. This combustion requires a constant and controlled supply of fuel, air, and spark.
When people talk about a full tune-up, they are talking about making sure these three items are well taken care of. The spark plugs give the spark, the fuel injectors give the fuel, and the throttle body controls the air. This is of course simplified; there are multiple hoses, relays, pumps, wires, sensors, etc. involved in the process. But for a basic understanding, this will work.
How does the motor harness the power from the mini explosions? The explosions mentioned earlier are contained inside of cylinders that have pistons which move up and down. These pistons are on what is called a crankshaft that all of the pistons are connected to. The pistons alternate on the shaft so that when one is up, the next one is down and so on. As the pistons move up and down, they spin the shaft. The spinning of the shaft is how the power from combustion is converted into something that can now be used power the vehicle.