This book is a short and simple introduction to biodiversity - how it arose, where it occurs, why it is important and what should be done to maintain it. Designed primarily with undergraduate students in mind, although also of interest to conservation and environment professionals, it provides a timely overview of the serious attempts made to quantify and describe biodiversity in a scientific way as well as acting as a point of entry into the primary literature. Incorporated into the text are a number of exercises designed to encourage active learning and promote debate of some of the more controversial issues.