This book is for the general reader who wants to know how science really works and to know how much authority to grant to experts; it is for the student studying science at school or university; and it is for those at the very beginning of a course in the history, philosophy or sociology of science. In sum, the book is for the citizen living in a technological society. The book adapts the work of professional historians and sociologists for a more general audience. The chapters are of different origins. Some are based on our own work and some on our readings of a selection of the few books and papers in the history and sociology of science that adopt a non-retrospective approach. In these later cases we have relied on the original authors for additional information, and have had occasional resource to archival material. In choosing chapters to represent science we have been limited by the materials to hand. But, given this constraint, we have covered the ground in two ways. We have selected from the life sciences and the physical sciences and we have selected episodes of famous science alongside relatively mundane science and what some would call bad science. We have done this because we want to show that, in terms of our concerns, the science is the same whether it is famous or infamous, big or small, foundational or ephemeral.