Flour is a powder made by grinding raw grains or roots and used to make many different foods. Cereal flour is the main ingredient of bread, which is a staple food for many cultures, making the availability of adequate supplies of flour a major economic and political issue at various times throughout history. Wheat flour is one of the most important ingredients in Oceanic, European, South American, North American, Middle Eastern, North Indian and North African cultures, and is the defining ingredient in their styles of breads and pastries.