An in-depth look into origami tessellation design, this book does not include traditional models such as flowers, animals, or insects, but rather remarkably intricate paper patterns known as tessellations. It follows the construction and analysis of six twists that are well-known to tessellation designers and explains how to use these twists to create generalized rules about the medium as a whole. Employing an accessible style, it describes the concepts in a way that is understandable to anyone with geometric curiosity.