In cooking, proofing (also called proving) 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, thereby leavening the dough.

In contrast, proofing or blooming yeast (as opposed to proofing the dough) may refer to the process of first suspending yeast in warm water, a necessary hydration step when baking with active dry yeast. Proofing can also 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.

Fermentation rest periods are not always explicitly named, and can appear in recipes as "Allow dough to rise." When they are named, terms include "bulk fermentation", "first rise", "second rise", "final proof" and "shaped proof".