Cellulose as an abundant renewable material has stimulated basic and applied research that has resulted in significant progress in polymer science. This book discusses reliable crystal structures of all cellulose polymorphs and cellulose derivatives. Models are represented in graphs, together with a collection of geometrical data and the atomic coordinates. The author briefly introduces fiber diffraction, computer-aided modeling and spectroscopic investigations, as well as the necessary molecular data from oligosaccharides as a basis for structure evaluations. X-ray diffraction patterns and spectroscopic diagrams are presented as references to characterize cellulosic materials and to serve as fingerprint tools for the exploration of unknown specimens of cell walls and of industrially processed films and fibers as well as solid-state materials. This book is a concise guide for the materials and life sciences communities interested in cellulose and related materials.