Those with an interest in knots, both young and old, will enjoy reading Why Knot? An Introduction to the Mathematical Theory of Knots. Colin Adams, well-known for his advanced research in topology and knot theory, is the author of this new book that brings his findings and his passion for the subject to a more general audience. Adams also presents a history of knot theory from its early role in chemistry to modern applications such as DNA research, dynamical systems, and fluid mechanics. Real math, unreal fun!Each copy of Why Knot? is packaged with a plastic manipulative called the Tangle®. Adams uses the Tangle because “you can open it up, tie it in a knot and then close it up again.” The Tangle is the ultimate tool for knot theory because knots are defined in mathematics as being closed on a loop. Readers use the Tangle to complete the experiments throughout the brief volume.Preface 0 Section 1: Introduction 1 Section 2: Mathematical Knots: What Are They? 5 A. The Basic Idea 5 B. Composition 9 C. Crossing Number 13 D. Reidemeister Moves 15 E. Links 19 F. Unknotting Number 27 G. How Many Knots Are There? 30 H. Denoting Pictures of Knots 34 Section 3: Knots, What Good Are They? 38 A. History 38 B. Knotted DNA 39 C. Knotted Molecules 41 D. Random Knotting 44 Section 4: The Future 45 Extra Fun 46 Appendix 1 48 Appendix 2 50 Further Reading 51 Some Answers to the Experiments 52