Preferment

A preferment is dough food that ferments before the dough: flour, water, and leaven, held until ripe, then mixed into the batch. Calvel treats preferments as part of technical breadmaking — flavor, maturity, and a different mix than a straight dough ¹. King Arthur Baking writes them as a formula line in Baker's percentage, then shows why you must also recast them into overall percent ².

The family is not one recipe.

Name	What it is in this corpus
Poolish	Yeast sponge; King Arthur's example is equal flour and water
Biga	Stiff yeast preferments as a family; no sourced hydration here
Pâte fermentée	Old dough, already salted
Levain	Build from sourdough starter for a specific dough

Prefermented flour is how much of the bread's flour lived in that piece. Inoculation is how much leaven you used. A poolish can preferment a lot of flour with almost no yeast in the sponge ².

What to notice #

Ripe: aerated, aromatic, still capable of lifting, not collapsed and sharp. As one line in a formula, a preferment makes water and salt look wrong until you split it. Failure is treating every sponge as levain, or copying a poolish hydration onto a biga because both are "preferments."