The primary structure of a glycan is consist of the nature and order of monosaccharide residues, the configuration and position of glycosidic linkages, and the nature and location of non-glycan entities to which they are attached. In addition, different glycans can be attached to different sites on a glycoprotein. Moreover, it is often three-dimensional features, or particular surface distributions of glycans, that are recognized by glycan-binding proteins. The structural characterization of glycans includes monosaccharide residue composition, sequence and linkage types. Characterization of these diverse structural features requires an array of different methods.