Grains are made of numerous tissues with distinct composition, structure and physiological role for the future plant. Grain processing methods are mainly focused on the isolation of the starchy endosperm to produce flour or semolina, the remaining products being recovered in the technological bran and short fractions. Fractionation diagrams are adapted according to cereal species, cereal grain structure and targeted end-products. Starchy endosperm accounts for about 60-85% of the harvested cereal grain by weight and can be recovered with milling. Flours, with specific characteristics and properties, can be extracted at different stages of the milling process. The percentage of dry grain mass corresponding to the germ, taking into account both the embryonic axis and the scutellum, differs depending on the cereal. Bran fractions are commonly recovered as a by-product of the milling industry. Future research has to select the most adapted cereal grains, cultivars and samples in relation with processing steps.