Grain husk is the outer layer of a grain, such as wheat or oats, and is composed of several parts. The BRAN, which is the outermost layer, is a rich source of dietary fiber, vitamins, and minerals. CHAFF is the dry, scaly protective covering of the grain, which is removed during threshing. Glume is the thin, papery husk that covers the grain and is usually removed during milling. All three components of the grain husk are important for human nutrition and are used in various food products.