Social Media Settings and safety.

How safe is your social networking site?  Can anyone get into it?  Even if settings are set to PRIVATE and ONLY ME... is there anyone who can access this?  GOOD Question and I need to research this to find out. I have learned long ago that anything you don't want the world to know... keep to yourself.  Do not give out any personal information no matter how much someone asks nicely to.  Even in the personal chats, I don't like to give out any information.  It is better to be over safe and protective than sorry!  I am currently cleaning up my facebook and checked my privacy settings.