Flour is the fine powder that comes from grinding grains or seeds. In earlier times, the milling of grain was done with stones. The flour is considered to be a primary food, as it is the raw first material for bread making. Today, there are many types of flour produced from different kinds of grain or seeds and by different grinding and sieving techniques. The most common kinds of flour are wheat, corn, barley and rye. The kind of flour you need to use depends on the recipe (for bread, pastry, sheet cake, cookies, cake, etc.).