What is the highly fibrous outer layer of grains including oats wheat maize?

The highly fibrous outer layer of grains including oats, wheat, and maize is known as the bran. Bran is composed of various layers, including the pericarp, seed coat, and aleurone layer. It is rich in dietary fiber, minerals, vitamins, and antioxidants. Bran is often removed during the milling process to produce refined grains, but it can be retained or added back to whole grain products to increase their nutritional value.