Paradoxical set

Okay, so imagine you have a set of things, like toys. And you want to make a set that has certain rules, like "this set doesn't have any sets inside of it". So you start picking out toys to put in the set, but as you do, you realize that some of them are sets themselves.

Now, that's where the paradox comes in. Remember, we made a rule that the set can't have any sets inside of it. But if there are sets inside of it, then it breaks the rule we set up in the first place. It's kind of like saying "I'm never going to say 'I'", but then you say it to explain the rule you made.

This type of set is called a paradoxical set because it has a contradiction or paradox within it. It seems like it should be impossible to exist, but some smart people have figured out ways to use them in math and logic. But for now, just remember that it's a set of things that breaks its own rules and makes our heads hurt trying to understand it.