Polysaccharides are organic polymers in which the repeating unit consists of monosaccharides. They exist in plants, animals, algae, or microbial worlds. Chitosan is a cationic linear polysaccharide of glucosamine produced from chitin deacetylation in alkaline media. Chitin is obtained from the exoskeleton of shrimps, crabs, and squids. Therefore, chitosan is environmentally benign and biodegradable. This book summarizes different aspects of chitosan and its derived materials, addressing isolation, properties, and applications. This book is intended for academics, professionals, and scientists as well as graduate and undergraduate students without any geographical limitations.