Microsatellites are short stretches of repeated DNA that show exceptional variability in humans and most other species. This variability has made microsatellites the genetic marker of choice for most applications, including genetic mapping and studies of the evolutionary connections between species and populations. This book brings together an international group of scientists currently working in microsatellites. They detail the molecular processes that have given rise to microsatellite DNA, and then describe the various ways in which the potential of microsatellites is being harnessed in medical genetics, behavioural and evolutionary biology, and ecology.