Okay kiddo, have you ever played with a big box of crayons and noticed that some colors are used up more than others? Imagine if you had a big box of crayons but you couldn't see what colors were inside. You had to pick a crayon at random and color with it.
Well, sometimes in real life, things work like that too. There is a thing called a "fading distribution" which means that some things are more likely to happen than others. For example, if you have a bag of M&M's, some colors might be more common than others. You might get more blue M&M's than green ones.
The "fading" in a "fading distribution" means that the chances of getting something decrease over time. So imagine you have a box of crayons but every time you pick one, it gets a little bit smaller. Eventually, you will run out of some colors before others.
Fading distributions can happen in all sorts of things, like the amount of money people have or how often it rains in a certain place. We use math to try to predict these things so we can make good choices. But even with math, it can still be hard to know for sure what color M&M you're going to get next!