Nazi concentration camps are by no means the only examples of these 'extreme institutions'; Dan Stone sets out the fuller story, from the Boer War to Bosnia. He shows how different regimes have used concentration camps at times of crisis to control populations that appeared threatening, and examines their role in consciousness and identity. The best Very Short Introductions will educate general readers, students, and academics alike. Speaking for my fellow academics, I have not been surprised to find how many of us esteem them as handy and reliable introductions to subjects on the more distant horizons of our professional knowledge. Stone's volume is outstanding in this respect, and it is as much a contribution to the field as a summary of it.