ELI5: Explain Like I'm 5

Idempotent element (ring theory)

Okay kiddo, let's imagine we have some kind of treasure box that we can play with. In this treasure box, we have different color balls that we can play with. Now, let's talk about a special kind of ball called an "idempotent ball".

An idempotent ball is a special kind of ball that you can throw multiple times and it will always end up in the same place. For example, let's say we have a red idempotent ball. If we throw it once, it will land in a certain spot. But if we throw it again, it will still land in the exact same spot as before.

Now let's imagine we have a whole bunch of different color idempotent balls in our treasure box. Some of these balls might be really good at staying in the same spot when we throw them, while others might not be so reliable. In ring theory, we call these reliable idempotent balls "idempotent elements".

An idempotent element is basically like an idempotent ball, but instead of bouncing around in a treasure box, it lives in a special kind of math world called a "ring". In this math world, you can add and multiply numbers together, just like you might have done in your math class.

Now, some of these numbers might be idempotent elements. This means that if you multiply them by themselves, you'll get the same number back again. Just like if you throw an idempotent ball multiple times, it will always end up in the same spot.

So to sum it up, an idempotent element is like a reliable idempotent ball that lives in a special math world called a ring. When you multiply an idempotent element by itself, you always get the same number back again. Pretty cool, right?