Origami, paper folding, originated hundreds of years ago in China and Japan, with independent discovery across the world. Today people do origami, create new models, share their work, and discover mathematical principles. This book continues the approach of Origami with Explanations; but is independent, with basic instructions repeated. Carefully written instructions, using photos and diagrams, will turn you into a successful folder and stimulate your own creativity. The models in this book include action models, money folds, beautiful and useful containers, and modular origami. Mathematics topics touched on include improving estimates, tessellations, mathematical induction, flat-foldability, and fold-and-cut. The Explanations section provide insight into the origami and introduce or re-introduce you to basic and advanced subjects in mathematics.