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

My favorite feature is the ability to append into registers by using capital letters. For example, say you want to move a subset of imports from buffer X to buffer Y.

1. Go to line x1 in buffer X.
2. Type "ayy to replace register a with the content of line x1.
3. Go to line x5.
4. Type "Ayy (capital A) to append line x5 at the end of register a.
5. Go to buffer Y and type "ap to paste