Eli Pariser is the board president and former executive director of MoveOn.org, which at five million members is one of the largest citizens' organizations in American politics. During his time leading MoveOn, he sent 937,510,800 e-mails to members in his name. He has written op-eds for The Washington Post and The Wall Street Journal and has appeared on The Colbert Report, Good Morning America, Fresh Air, and World News Tonight.

In December 2009, Google began customizing its search results for each user. Instead of giving you the most broadly popular result, Google now tries to predict what you are most likely to click on. According to MoveOn.org board president Eli Pariser, Google's change in policy is symptomatic of the most significant shift to take place on the Web in recent years-the rise of personalization. In this groundbreaking investigation of the new hidden Web, Pariser uncovers how this growing trend threatens to control how we consume and share information as a society-and reveals what we can do about it.Though the phenomenon has gone largely undetected until now, personalized filters are sweeping the Web, creating individual universes of information for each of us. Facebook-the primary news source for an increasing number of Americans-prioritizes the links it believes will appeal to you so that if you are a liberal, you can expect to see only progressive links. Even an old-media bastion like T