This book is about the fine print in contracts: the terms that individuals sign without reading when they click “I agree” or buy a plane ticket or engage in any common market transaction. The book explores the relation between this phenomenon and the ideal of consensual contracts. It identifies problems that the unreadable language creates and how this affects the welfare of individuals. It reveals what it is that we truly agree to when we accept these mass-distributed contracts. And it explains how business uses these contracts to gain advantages, but also, in a variety of subtle ways, to improve competition.