Oligosaccharide is a class of carbohydrates. Carbohydrates are a large class of chemical compounds that includes sugars, starches, cellulose, and related compounds. These compounds are produced naturally by green plants from carbon dioxide and water. Carbohydrates are important as foods; they supply energy and are used in the production of fats. There are three classes of carbohydrates: monosaccharides, which are the simple sugars like fructose and glucose; disaccharides. which include lactose, maltose, and sucrose; and polysaccharides, which include cellulose, dextrin, glycogen, and starch. They are polymeric compounds made up of the simple sugars and can be hydrolyzed to yield simple sugars. The disaccharides are sometimes grouped with the simpler polysaccharides to form a class of carbohydrates called the oligosaccharides.