At first, all grains are whole grains. A whole grain is the plant's entire seed. It is composed of three parts, which are all edible. These parts are the bran, the germ, and the endosperm. These parts are shielded by a husk, which you actually cannot eat. This shield protects the whole grain from outside dangers, such as pests, too much or too little sunlight, and too much or too little water. Hope this helps.