Glycolipids are lipids with a carbohydrate attached by a glycosidic bond. Their role is to serve as markers for cellular recognition and also to provide energy. The carbohydrates are found on the outer surface of all eukaryotic cell membranes. They extend from the phospholipid bilayer into the aqueous environment outside the cell where it acts as a recognition site for specific chemicals as well as helping to maintain the stability of the membrane and attaching cells to one another to form tissues