Innovations are adopted when users integrate them in meaningful ways into existing social practices. Histories of major technological innovations show that often the creative initiative of users and user communities becomes the determining factor in the evolution of particular innovations. Theevolutionary routes of the telephone, the Internet, the World Wide Web, email, and the Linux operating system all took their developers by surprise. Articulation of these technologies as meaningful products and systems was made possible by innovative users and unintended resources.Iterative and interactive models have replaced the traditional linear model of innovation during the last decade. Yet, heroic innovators and entrepreneurs, unambiguous functionality of products, and a focus on the up-stream aspects of innovation still underlie much discussion on innovation,intellectual property rights, technology policy, and product development. Coherent conceptual, theoretical and practical conclusions from research on knowledge creation, theory of learning, history of technology, and the social basis of innovative change have rarely been made.This book argues that innovation is about creating meaning; that it is inherently social; and is grounded in existing social practices. To understand the social basis of innovation and technology development we have to move beyond the traditional product-centric view on innovations. Integratingconcepts from several disciplinary perspectives and detailed analyses of the evolution of Internet-related innovations, including packet-switched computer networks, World Wide Web, and the Linux open source operating system, the book develops foundations for a new theoretical and practicalunderstanding of innovation. For example, it shows that innovative development can occur in two qualitatively different ways, one based on evolving specialization and the other based on recombination of existing socially produced resources. The expanding communication and collaboration networks haveincreased the importance of the recombinatory mode making mobility of resources, sociotechnical translation mechanisms, and meaning creation in communities of practice increasingly important for innovation research and product development.