A blog is a diary without a key

A blog is a place where you're supposed to write about things you're thinking about or experiencing. But do some people have both private and public blogs? There are a lot of things I think about but I wouldn't want out there so public. Maybe you could read it, but not you. Get it? I've read a lot of blogs and sometimes I'm amazed at the private stuff that is shared. Don't the writers realize that anybody could read their thoughts? Or is that the point? Is blogging just another form of exhibitionism? Exhibition of the soul? That's probably more intimate than any other kind.