A ferment is easy to make and usually consists of a simple mixture of wheat flour, water, and a leavening agent (typically yeast). Two schools of thought exist regarding the inclusion of salt or sugar. They both act to inhibit or slow yeast growth, as determined by time to proof or rise, so they are not usually included and instead are added to the final dough. Ultimately, the amounts of each ingredient, and when they are added, depend on pre-ferment and final-dough formulas.