Hard wheat is wheat with hard, vitreous kernels and a high protein — and therefore high gluten — content, the miller’s choice for bread flour. The hardness reflects a tight bond between starch and protein in the endosperm, which shatters into coarse particles on milling and yields strong, elastic doughs that trap fermentation gas for well-risen loaves. Hard wheats — typically 12–15% protein — are grown in continental climates such as the North American prairies and are traded globally as bread-making wheat. They contrast with soft wheats, whose weaker gluten suits cakes, biscuits, and pastry. Durum, the hardest of all, is reserved for pasta. Flour “strength” begins in the wheat field.