Knaster–Tarski theorem

The Knaster-Tarski Theorem is like a magic trick that helps us understand something called "fixed points". Imagine a wizard who wants to draw a picture of himself, but every time he draws it, the picture changes a bit, so he can never really see what he looks like. This is like a "fixed point": no matter what you do, things stay the same. But the Knaster-Tarski Theorem tells us that if we have some rules (called "lattices") that make sure no matter how we draw the wizard, it will always end up looking like him. It's kind of like tracing an outline and then coloring it in no matter how you arrange the wizard's clothes or other details. This magic trick helps us understand how things stay the same even when they seem to change, just like how the wizard can always look like himself no matter how many times he tries to draw himself.