Proofing (baking technique)
In cooking, proofing (North American) or proving (British and Australasia) 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.
Source: Wikipedia — Proofing (baking technique) (CC BY-SA 4.0)