Flour is a powder made by grinding raw grains, roots, beans, nuts, or seeds. It is used to make many different foods. Cereal flour is the main ingredient of bread, which is a staple food for most cultures. Wheat is the most common base for flour, as is corn flour and rye flour. Cereal flour consists either of the endosperm, germ, and bran together (wholegrain wheat flour) or of the endosperm alone (all purpose flour).