ELI5: Explain Like I'm 5

Train on Train

So, you know how trains are big vehicles that move on tracks? Well, sometimes there are smaller trains that run on the back of the big trains. Kind of like how you might have a toy car that fits on the back of a toy truck.

These smaller trains that run on the back of the big trains are called "train on train". They can carry things like freight (which is stuff that's being transported from one place to another), or even passengers (which are people who are traveling somewhere).

Now, you might be thinking, "How can a train run on the back of another train without falling off or getting squished?" Well, it's all thanks to special hooks and connectors that keep the trains attached to each other. Kind of like how you might use a clip or a hook to attach two things together.

And just like how you can have multiple cars in a toy train set, there can be multiple small trains on the back of a big train. They can all be connected together and move as one big train.

So, that's the basics of train on train! It's when smaller trains run on the back of bigger trains, using special hooks and connectors to stay attached. They can carry things like freight or passengers, and there can be multiple small trains on the back of one big train.