Is there an ELI5 video / tutorial for all things box-variables that you can recommend? I understand pointers, I understand references, I understand ownership a

Is there an ELI5 video / tutorial for all things box-variables that you can recommend? I understand pointers, I understand references, I understand ownership and mutability. I feel lost with Box things. The official documentation came across as cryptic to me and I had a hard time getting over the syntax. Like, what is "T" and why does it get passed into Box<> ... etc.