Book excerpt: This book focuses on the mechanical properties and performance of products made of fiber-based materials. It helps students to develop skills for solving problems of product performance and engineering challenges in product development. Organized with a problem-based approach - practical examples of product performance are presented and the relevant mechanics are analyzed to deduce which material properties control the performance. The new edition covers state-of-the-art and green technologies as modeling of fiber networks and applications of nanocellulose.