Can someone explain what does deadstock mean? Is it worth the hype?

Hey everyone,
I’ve been seeing the term "deadstock" thrown around a lot lately, especially in sneaker and fashion communities. Can someone explain what does deadstock mean? Like, is it just old stuff that never got sold, or is there more to it?

I’ve heard people say it’s super rare and valuable, but idk if it’s worth the hype. Like, why would someone pay extra for something that’s been sitting in a warehouse for years?

Also, does it have to be brand new, or can it be lightly used? I’m kinda confused about the whole thing.

Thanks in advance for clearing this up! 🙏