External combustion engine

An external combustion engine is like a machine that can turn energy into movement, but it uses heat from a fire to make things go instead of burning fuel or gas inside the machine, like your car.

Think of it like this - you know how when you're sitting around a campfire, you can feel the heat coming from the flames, and your marshmallow or hot dog gets cooked over the fire? Well, an external combustion engine works sort of like that fire.

The fire, which is usually fueled by coal, wood or natural gas, heats up something called a "boiler" which is like a big metal pot with water inside. When the water boils and turns into steam, the steam rises up and is used to spin a big wheel or piston like in a steam train.

This spinning is what makes the engine work, and it can then be used to power things like boats, generators or even factories.

So, in summary, an external combustion engine is a machine that uses heat from an external fire to make steam spin a big wheel or piston and provide power for other things.