Can I just ask please? I'm currently in the very early stages of writing my book but I feel it has a lot of potential because it is very different and controversial. If I wanted to put a synopses of it on here just to get some initial feedback, how does it work in terms of the possibility of somebody else reading it and deciding to take it for themselves to turn into their own book?
By no means am I an expert on publishing or copyright, but why take the risk? You might not even have recourse in the event of someone developing your idea -- remember that this is a public site that doesn't require membership. I would phrase your concerns in generalities if those questions are permitted under this site's terms of use, given your membership status (of which I've forgotten for your circumstance).
Well, if someone wrote a story based on your synopsis, I wouldn't think that would be any kind of copyright infraction at all, unless they used names/places/etc that you made up yourself. If they write a story from that, it's an improbable thought that they would write the exact same story anyway. That being said, it's something that can be done even after your book is published and on the shelves. They see your book, read the synopsis, and BAM! Story idea.