This book illustrates key mathematical aspects of the Golden Ratio: It particularly delves into geometric and number theoretical connections and examples, and makes further considerations and generalizations accessible. The book is primarily aimed at students, pupils, mathematics teachers, and interested laypeople. It is modular in structure, so the individual chapters can be read independently of one another. The reading is intended to encourage one's own geometric activities. Tips and procedural hints from the craft-creative realm are also provided. Supplementary animations can be accessed with the SN More Media App: simply download the SN More Media App for free, scan a picture or link with the play button, and immediately play the animation on your smartphone or tablet. The translation was done with the help of artificial intelligence. A subsequent human revision was done primarily in terms of content.