It can bedivided into three broad categories: structural and modulatory properties, including nutrient storage and sequestration, specific recognition by other molecules most commonly, glycan-binding proteins (GBPs) and molecular mimicry of host  glycans.

 Cells are endowed with a rich surface coat of glycans that are carried as glycolipids on the outer leaflets of their plasma membranes and constitute a major molecular interface between cells and their environment. Each cell's glycome, the sum of its diverse glycan structures, comprises a distinct cellular signature defined by expression levels of the enzymes responsible for glycan 

Glycan, alongside  DNA, proteins and lipids. They are essential for multicellular life, as the complete absence of glycans is embryologically lethal . They are the most abundant and diverse natural , biopolymers composed  of saccarides that are typically added to nascent proteins and lipids within the cell secretory pathway  (endoplasmatic reticulum and Golgi apparatus). The glycome represents the entire glycan repertoire osef an organism,tissue,cell,protein.

Pathogen infection typically begins with host  glycan recognition and binding by one or more of viral, bacterial, or protozoan  numerous  lectins. The first identified microbial lectin was the hemagglutinin from the influenza virus. A glycoprotein itself, its name originates from the ability to crosslink red blood cells by binding to terminal sialic acids on their surface. Influenza hemagglutinin is one of the best studied lectins and its specific recognition of distinct glycan structures.

Many recombinant pharmaceuticals, including therapeutic monoclonal antibodies are glycoproteins  and their specific glycoforms are the key to their bio-activity and half lives in circulation glycans  attached to Fc domain modulates effector functions of monoclonal antibodies and tuning of glycosylation to desired effector functions can improve efficacy of the drug Glycans constitute about 40% of its molecular weight and differentiate between different glycoprotein variants sharing the same polypeptide sequence.

Selectins are a family of cell surface lectins originally identified as key initiators of inflammation. All selectins function by binding to specific glycoprotein and glycolipid ligands on the cell surface in a calcium-dependent manner. They play a significant and a well-documented role in leukocyte recruitment and migration to sites of inflammation, initiating tethering and rolling of circulating leukocytes that leads to their activation, adhesion and subsequent extravasation into tissues, as well as signal transduction.

In cells, monosaccharides are linked together to create elaborate structures through glycosidic bonds. Complex glycans also arise from the multiple possible attachment points between sugar units (regiochemistry and branched structures) as well as from the stereochemistry of glycosidic bonds (a-glycosides).

Glycans are key players in many biological processes. They are essential for protein folding and stability and act as recognition elements in cell–cell and cell–matrix interactions. Thus, being at the heart of medically relevant biological processes, glycans have come onto the scene and are considered hot spots for biomedical intervention. The progress in biophysical techniques allowing access to an increasing molecular and structural understanding of these processes has led to the development of effective therapeutics.

Glycomics is the comprehensive study of glycomes (the entire complement of sugars, whether free or present in more complex molecules of an organism), including genetic, physiologic, pathologic, and other aspects. Glycomics "is the systematic study of all glycan structures of a given cell type or organism" and is a subset of glycobiology. The term glycomics is derived from the chemical prefix for sweetness or a sugar, "glyco" and was formed to follow the omics naming convention established by genomics (which deals with genes) and proteomics (which deals with proteins).