Private companies ranging from casinos and credit companies to the website of Led Zeppelin guitarist Jimmy Page know much more about us than the NSA. What, if anything, can you do to control your personal information, and prevent people from using it against you? Harvard University Institute for Quantitative Social Science fellow Adam Tanner, author of What Stays in Vegas: The World of Personal Data--Lifeblood of Big Business--and the End of Privacy as We Know It, explains how our information came to be harvested and manipulated, whether we like it or not, and what can be done to protect ourselves.