If you have never bothered to touch the privacy settings on the site, then your details and postings are set to public - public, as in, 'don't even need an account to see it', public.

You privacy is all you have. Even if you have been through the privacy settings on Facebook, please, please please please visit this site anyway:

http://www.reclaimprivacy.org/

I  thought I'd got everything in check, and I pretty much had bar one thing: my friends could accidentally share my details with third parties - a problem that is easy to fix using this site.

This is not a scam, not a 'virus', as you'll see. I am deadly serious. It's quick, safe and easy to do. I can't make you do it - but I wish I could.

You don't have to leave Facebook (although I am coming close), and it can be a safe, private network - they just don't make it very easy.

Facebook have recently made changes to their privacy policy, and now, frankly, they are taking the piss. It's still safe to use, but you have to visit that link above to make sure.

Maybe you're thinking 'so what, I don't care what people see'. That's fine - but at least find out exactly what's going on with your account: stay on top of it rather than just assuming you know. The prospect of a wall message you sent to a friend being searchable on Google doesn't appeal to most people.