Is private regulation of the Internet over? Have states taken over? This book examines the function of self-regulation in cyberspace. It argues that, contrary to what is often supposed in the literature, self-regulation is still an indispensable part of regulation of the Internet and will arguably remain so. It is intricately woven in the mesh of rules that governs the Internet today. Private regulation fills substantive or procedural gaps where no state regulation exists or where it is incomplete or ineffective, thus complementing the reach of state regulation. Simultaneously, states supply legal (and financial) frameworks that enable or complement self-regulation. In practice, often unknown to users, their behaviour is regulated by intertwined rules coming from both states and private groups. While each source of rules retains its identity and regulatory strengths, it is dependent on and complementary to the rules and processes of the other to effectively regulate Internet activities.