Chitosan is a linear polysaccharide composed of randomly distributed β-(1→4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). Due to its physical and chemical properties, chitosan is being used in a vast array of widely different products and applications, ranging from pharmaceutical and cosmetic products to water treatment and plant protection. Chitosan is produced commercially from chitin, which is the building material that gives strength to the exoskeletons of crustaceans (crab, lobster, and shrimp), insects, and the cell walls of fungi. Through enzymatic or chemical deacetylation, chitin can be converted to chitosan. The degree of deacetylation (%DD) can be determined by NMR spectroscopy, and the %DD in commercial chitosan ranges from 60 to 100%. The molecular weight of commercially produced chitosan is between 3,800 and up to 400,000 Daltons. Our chitosan can also be categorized by its application, such as research, medical, cosmetic and food grades.