What the Hell Is Emptiness?

There are different kinds of emptiness practice. But in a particular tradition that I've been doing a bunch of meditation in recently, they'll put that mind only meditation in a sequence with other kinds of emptiness meditation. So it's not as though, it's not idealism in the sense that mind really gets to have inherent existence. It's just the world that doesn't. You know what I mean? It's like both are empty in some sense.