How do I use vim registers?

Question

I only know of one instance using registers is via CtrlR* whereby I paste text from a clipboard.

What are other uses of registers?

Answer 1

The black hole register _ is the /dev/null of registers.

I use it in my vimrc to allow deleting single characters without updating the default register:

noremap x "_x

and to paste in visual mode without updating the default register:

vnoremap p "_dP