Glycans are mono- or oligosaccharides bound to lipids or amino acids with glycosidic linkages to form "glycoconjugates". These structures are often found within polypeptides or proteins. The carbohydrate component is named "glycone", the non-carbohydrate "aglycone" (Seeberger 2015-2017). In this sense, glycans are not carbohydrates, because other molecules are linked to the carbohydrate core.

The term glycan refers to the carbohydrate domain within protein-carbohydrate molecules (proteoglycans) or lipid-carbohydrate molecules (glycolipids). Glycan structures are built from glycosidically linked monosaccharides and demonstrate receptor or binding function in various cell types (Taylor and Drickamer. 2014). Some human milk oligosaccharide isoforms have a similar structure and use it for the decoy effect.

Glycans are a diverse group of molecules often with complex (3D) structures linking to other glycans or carbohydrates with a multitude of biological functions described in detail here: (Varki et al. 2015-2017b). Glycans are involved in cell-surface interactions regulating cell differentiation, recognition, and proliferation or support cell walls of plants and microbes mechanically (Prestegard et al. 2015-2017). Human milk oligosaccharide