In 17 chapters, this book attempts to deal with well-known and less well-known topics in mathematics. This is done in a vivid way and therefore the book contains a wealth of colour illustrations. It deals with stars and polygons, rectangles and circles, straight and curved lines, natural numbers, square numbers and much more. If you look at the illustrations, you will discover plenty of exciting and beautiful things in mathematics. The book offers a variety of suggestions to think about what is depicted and to experiment in order to make and check your own assumptions. For many topics, no (or only few) prerequisites from school lessons are needed. It is an important concern of the book that young people find their way to mathematics and that readers whose school days are some time ago discover new things. The numerous references to internet sites and further literature help in this respect. "Solutions" to the suggestions interspersed in the individual sections can be downloaded from the Springer website. The book was thus written for everyone who enjoys mathematics or who would like to understand why the book bears this title. It is also aimed at teachers who want to give their students additional or new motivation to learn. This book is a translation of the original German 2nd edition Mathematik ist schn by Heinz Klaus Strick, published by Springer-Verlag GmbH, DE, part of Springer Nature in 2019. The translation was done with the help of artificial intelligence (machine translation by the service DeepL.com). In the subsequent editing, the author, with the friendly support of John O'Connor, St Andrews University, Scotland, tried to make it closer to a conventional translation. Still, the book may read stylistically differently from a conventional translation. Springer Nature works continuously to further the development of tools for the production of books and on the related technologies to support the authors.