Two years old ginger is not newly dug. Ginger usually refers to tender ginger, which has just been dug out. Its skin is smooth, light yellow and has few fibers. It is best for cooking or pickling sour ginger. The skin of old ginger is yellow, rough and spicy, and the fiber is thick. Ginger is usually used as seasoning in cooking and stewing, and needs to be cut or broken to taste. Young ginger is not easy to preserve, but it can be preserved for a long time. Ginger is the fresh rhizome of ginger, which is mild and pungent, and belongs to lung, spleen and stomach meridians. The chemical constituents of ginger include volatile oil, terpenoids, resins, amino acids, flavonoids and so on. Among them, volatile oil is the main active ingredient.