Think about what you put on facebook. If you're like most people, there is something in your photos, comments, likes, etc. that could get you into trouble. I Know Who You Are and I Saw What You Did explores the many ways that social networking websites expose individuals to physical and legal abuse. Written by an attorney, the book has a legal emphasis, with many chapters on how publicly-visible facebook posts can prejudice judges against one claimant over another, or function as evidence not admitted in court when jurors begin googling people. In many of the instances recorded here, the exposure comes not from people being careless, but from sites' privacy settings being adjusted without their knowing -- or because technology was being used to switch on their webcams without their awareness. Because of this, the author argues for a 'constitution' that would govern 'facebook nation', in essence a digital bill of rights protecting people. Having read Future Crimes and Data and Goliath, this was old hat for me, but a distilled reminder is always a good thing. The catchy title and comparative slimness might draw in readers who ignore those other works, as well. Very few congressional officials seem to know anything about cybersecurity, so I doubt we'll have a cyber bill of rights any time soon -- especially when easy violations of privacy serve the national security state so well. In the meantime all we can do is stay paranoid.