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

One overlooked register is the '.' dot register which contains the last inserted text no matter how it was inserted eg ct] (change till ]). Then you realise you need to insert it elsewhere but can't use the dot repeat method.

 :reg .
 :%s/fred/./