The vast circulations of mobile devices, sensors and data mean that the social world is now defined by a complex interweaving of human and machine agency. Key to this is the growing power of algorithms – the decision-making parts of code – in our software dense and data rich environments. Algorithms can shape how we are retreated, what we know, who we connect with and what we encounter, and they present us with some important questions about how society operates and how we understand it. This book offers a series of concepts, approaches and ideas for understanding the relations between algorithms and power. Each chapter provides a unique perspective on the integration of algorithms into the social world. As such, this book directly tackles some of the most important questions facing the social sciences today. This book was originally published as a special issue of Information, Communication & Society.