Polymeric saccharides can have 10,000 or more sugar units, four or five different sugars, and a branched structure. The diversity that can be envisioned is huge and much of it is actually observed. Classification of polysaccharides differentiates homopolymers (a single sugar type) and heteropolymers (two or more sugar types) with subtypes reflecting linear or branched structures within each group. Thephysical andbiological properties of eachpolymer depend on the architecture of the molecule as well as the enzymatic machinery available to interact with it. Thus, cellulose, a linear β-1-4 glucose polymer is a stable, highly organized polymer, indigestible by man, whereas starch, its α-linked counterpart is a major food source for all mammalian species.