Flour

Flour is a powder which is made by grinding cereal grains, other seeds or roots (like Cassava). It 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 foods in European, North American, Middle Eastern, Indian and North African cultures, and is the defining ingredient in most of their styles of breads and pastries.
Maize flour has been important in Mesoamerican cuisine since ancient times, and remains a staple in much of Mexico and parts of Central America.
Rye flour is an important constituent of bread in much of central Europe.