Bread dough is a mixture of flour, water, yeast, and salt that is used to make bread. The flour provides the structure, while the water activates the gluten, giving the dough its elasticity. Yeast is a living organism that ferments the sugars in the flour, producing carbon dioxide gas, which causes the dough to rise. Salt enhances flavor and controls yeast activity. To make bread, the ingredients are combined and kneaded to develop the gluten. After kneading, the dough is allowed to rise, or proof, which can take from one to several hours. Once risen, the dough can be shaped and baked to create various types of bread, such as sourdough, baguettes, or whole wheat bread.