Third rail

Okay kiddo, imagine you're playing with your toy train set. You have a track and a train that runs on it. Now, imagine there's another rail that's not like the other two. This rail has electricity running through it, and it's called the third rail.

The third rail is like a secret magic rail that gives energy to the train so it can move. It's usually hidden from you so you don't touch it, because it can be very dangerous. It's how trains and subways get power to move without needing gas like a car.

When the train or subway touches the third rail, it gets the energy it needs to move. It's kind of like when you plug in your toy car to recharge its battery. The third rail is how the train or subway does that, but without needing to stop and be plugged in.

So, that's the basic idea of the third rail. Just remember, be careful around it and always leave it to the experts to work with.