Glycans are a type of sugar, consisting of monosaccharides linked together like chains. By linking to proteins and lipids in the body, glycans not only regulate their functions, but also play an important role in cell recognition and adhesion processes, which are involved in supporting life itself. Another of their functions is determining the timing of protein metabolism, with the life span of proteins in the body or blood determined by the glycans linked to them. At the same time, glycans are drawing attention as the third most important life chain for unraveling the mysteries of biological phenomena, behind the nucleic acids and proteins responsible for the diverse evolution of living organisms.