Information is public?

I have created a form that I want to put on my website. I want anyone from the "public" to be able to enter information so it needs to be "Public" right? (ie: they don't have a username and password to use the form) But from what I am reading, it appears to me that by making the form public, I am also making my database (which is created from information the form collects) public and searchable by google? Is this correct? If so, is there a way to allow anyone to enter information in form on my website, while keeping the information they entered private?
neil.white