What Is the Fermi Paradox?

We expect aliens, but they're not showing up. Imagine you live in a big neighborhood with lots of houses, each house could have people living in it. But when you knock on the doors, no one answers. That's like the Fermi Paradox. We know there are many planets out there, so we think aliens should be around too. But if they're not here or we can't find them, that’s a big mystery. Maybe they’re hiding, or maybe they don’t want to be found.