Cellulose, the essential structural material in the vegetable kingdom, occurs in the form of elongated cells, or fibers. Due to a combination of favorable characteristics, such as high tensile strength, flexibility, a hygroscopic nature combined with insolubility in water, and an ability to form fiber-fiber bonds after beating, these fibers have been widely exploited for the manufacture of both paper and textiles. These characteristics are a consequence of the highly crystalline, polysaccharide nature of natural cellulose, and the morphology of the fibers themselves, which is based on concentric layers of spiraling, cellulosic fibrils. Cellulose in paper and textiles differs in four fundamental ways: 1) in the structure of the material; 2) in the physical state of the fibers; 3) in the chemical purity of the fibers; and 4) in the extent of the degradation of the cellulose. Generally speaking, cellulose fibers in paper have been the subject of more extensive physical and chemical assault than those found in textiles. Paper and cellulosic textiles differ markedly in their response to wetting: paper becomes significantly weaker when wetted, whereas cellulosic yarn may increase in strength on going from a dry to a wet state (assuming the cellulose is not too degraded).