Reparse versus parse

Hello,

I have a question on the reparse versus parse (soft or hard parses I assume), and if someone please explain under what circumstances a sql gets reparsed, and wonder if a reparse could be soft parse or hard parse.

I read some oracle documents taking about about avoid reparsing.  However, I have a hard time to understand exactly what constitute a reparse, and what's the difference between a parse and reparse, where soft parse is fine but reparse is not.  There must be a difference.  If I have a cursor open/close inside a loop, and I can see it will get reparsed every time since the cursor is closed.  But if the cursor is still in library cache and the open/close is not inside a loop, why it needs to be reparsed.