This extraordinary book explains the engine that has catapulted the Internet from backwater to ubiquity - and reveals that it is in danger precisely because of its runaway success. With the unwitting help of its users, the Internet and PC are on a path to a lockdown, ending their cycles of innovation - and facilitating unsettling new kinds of control. iPods, iPhones, Xboxes, and TiVos represent the first wave of Internet- centered products that can't be easily modified by anyone except their vendors or selected partners. These "tethered appliances" have already been used in remarkable but little known ways: car GPS systems have been reconfigured at the demand of law enforcement to eavesdrop on the occupants at all times, and digital video recorders have been ordered to self-destruct thanks to a lawsuit against the manufacturer thousands of miles away. New Web 2.0 platforms like Google mash-ups and Facebook are rightly touted - but their applications can be similarly monitored and eliminated from a central source. As tethered appliances and applications eclipse the PC, the nature of the Internet - its "generativity" that permits anyone, anywhere to build on it - is at risk. The Internet's current trajectory is one of lost opportunity. Its salvation, Zittrain argues, lies in the goodwill of its millions of users. Drawing on generative technologies like Wikipedia that have so far survived their own successes, Zittrain shows how to develop new technologies and social structures that allow users to work creatively and collaboratively while avoiding the excesses and abuses of openness - and to preserve the promise of the Net.