Glycogen is a polysaccharide made up of almost $2000-200000$ units of $\alpha-$ D glucose, it is a branched structure, there are two types of bonds present in glycogen as the $\alpha 1-4$ glycosidic and $\alpha$ 1- 6 glycosidic bond.
Glycogen stores in cells of liver and muscles and gives the red color with iodine also it is named as animal starch.