The primary ingredient in baking bread is flour. Typically made from wheat, flour provides the necessary gluten, which gives bread its structure and elasticity. When flour is mixed with water and kneaded, proteins in the flour form gluten strands, trapping air bubbles released by yeast during fermentation. This process is essential for creating the light, airy texture characteristic of well-baked bread. While other ingredients like yeast, water, and salt play supporting roles, flour is the star of the show, forming the crucial base of most bread recipes and influencing the final loaf's flavor and texture.