Saccharide is another name for a carbohydrate. Simple saccharides are the monosaccharides, commonly called sugars. Glucose is an example of a monosaccharide. Others are shown in Figure 9.9a and Figure 9.9b. We use the terms monosaccharide, oligosaccharide, or polysaccharide to refer to compounds composed of a single sugar, several sugars linked together, or many sugars linked together, respectively.

The term carbohydrate derives from the fact that many of them have a formula that can be simplified to (CH2O)n. Some of these compounds are chemically modified, however, and do not fit the formula due to the modification.

Saccharides play a variety of roles in living organisms, including energy storage (monosaccharides and oligosaccharides), structural roles (polysaccharides), and cell identity (oligosaccharides).