Proofing is a step in the preparation of yeast bread and other baked goods in which the dough is allowed to rest and rise a final time before baking). During this rest period, yeast ferments the dough and produces gases, which cause the dough to expand and become puffy. Proofing is also called final fermentation, and it is a crucial step in bread making that is key to breads structure, oven spring, and the beauty of the final loaf.

Proofing can refer to the process of testing the viability of dry yeast by suspending it in warm water with carbohydrates (sugars). If the yeast is still alive, it will feed on the sugar and produce a visible layer of foam on the surface of the water mixture).

A dough proofer is a warming chamber used in baking that encourages fermentation of dough by yeast through warm temperatures and controlled humidity. It is also called a proofing box, proofing oven, or proofing cabinet. The warm temperatures increase the activity of the yeast, resulting in increased carbon dioxide production and a higher, faster rise).

Bread dough is usually left to rise two different times in the baking process, and proofing technically refers to just the second of these rises but is often used to describe both. Properly proofed bread has had sufficient fermentation time but not too much, and it results in bread with a tall rise, delicate structure, pleasant eating quality, and abundant flavor.