Internal combustion engine
There are many kinds of internal combustion engine but the term often means the machine that Niklaus Otto invented.  In this kind, fire makes pressure increase inside a sealed box (cylinder). The pressure pushes a rod which is attached to a wheel. The rod pushes the wheel and makes it spin around. The spinning wheel is attached to other wheels, such as four car wheels, with a belt or a chain. The engine is very strong and can make all the wheels move.