Sourdough has its own vocabulary, and that vocabulary trips up almost every new baker. Recipes casually mention “levain,” “autolyse,” “bulk,” and “75% hydration” as if everyone already knows what they mean. This page is the plain-English reference: the concepts people ask about most, followed by a glossary of the terms you’ll meet again and again.
The big picture: what sourdough actually is
Sourdough is bread raised by a living culture instead of a packet of yeast. That culture — the starter — is a community of wild yeast and lactic-acid bacteria living in a simple mix of flour and water. The yeast produces gas that makes the dough rise; the bacteria produce acids that give sourdough its tang and help preserve the loaf.
Everything else flows from that one idea. Because the culture works slowly, fermentation takes hours rather than minutes. Because it’s alive, it needs feeding and responds to temperature. And because there’s no standardised commercial yeast doing the work, you learn to read the dough rather than follow a stopwatch.
Starter vs levain
This is the single most common point of confusion, so it’s worth being precise.
Starter (mother culture) The culture you keep alive indefinitely — you feed it, store it, and never use all of it. See the [active starter guide](/sourdough/active-sourdough-starter/).
Levain A fresh build made from a small portion of that starter for one specific bake. You grow it to the size the recipe needs, let it ripen, and use the whole thing.
In practice, many home bakers blur the line and just call a peak-ripe starter their levain. To size a build precisely, the levain calculator does the math. The feeding ratio guide explains how much fresh flour and water to feed it.
Why is my bread dense, gummy, or flat?
These are the classic beginner problems, and they almost always trace back to fermentation. Match the symptom to the likely cause:
Dense and flat usually under-fermentation or a weak starter — the [dense sourdough guide](/sourdough/why-is-my-sourdough-dense/) walks through it.
Gummy crumb often sliced before cooling or slightly underbaked — check the [internal temperature guide](/sourdough/sourdough-internal-temperature/).
Spreads, won't hold shape likely [over-proofed](/sourdough/overproofed-sourdough/) or too high in hydration for your flour.
Hydration and discard basics
Two more terms that come up constantly.
Hydration Water weight as a percentage of flour weight. More water = a wetter, more open crumb but stickier dough. Beginners do best around 65–70%. The [hydration calculator](/sourdough/sourdough-hydration-calculator/) keeps flour and water balanced.
Discard The portion removed before feeding so the culture stays strong. Not waste — it makes excellent pancakes, crackers, and waffles. Fridge storage with weekly feeding cuts down how much you discard.
Is sourdough actually healthier?
The long, slow fermentation predigests some of the starch and gluten and tends to lower the bread’s glycaemic impact compared with fast commercial loaves, and the acids can improve mineral availability. It’s still bread and still carbohydrate-rich, but many people find genuine long-fermented sourdough gentler on digestion than standard supermarket bread.
Sourdough glossary
Keep this list nearby while you bake — these terms show up in nearly every recipe.
Starter (mother culture) the living mix of flour, water, wild yeast, and bacteria that leavens your bread; maintained indefinitely.
Levain a fresh build of culture made from a portion of your starter for a single bake.
Feeding (refreshing) adding fresh flour and water to renew the starter's food supply; the proportions are the feeding ratio.
Discard the portion removed before feeding so the culture doesn't grow endlessly; usable in many recipes.
Hydration water weight as a percentage of flour weight; sets how wet and open the dough and crumb are.
Autolyse a rest after mixing just flour and water that hydrates the flour and jump-starts gluten.
Bulk fermentation (first rise) the long fermentation of the whole batch after mixing and before shaping.
Stretch-and-fold gently stretching and folding the dough during bulk to build gluten without kneading.
Shaping / pre-shaping forming the dough into a taut round or oval that holds structure; a light pre-shape precedes the final shape.
Proofing (final proof) the last rise after shaping, before baking — often done cold in the fridge.
Cold proof (cold retard) proofing the shaped loaf in the fridge 8–16 hours to deepen flavour and ease scoring.
Banneton a cane or wood-pulp basket that supports the shaped loaf and leaves the spiral pattern.
Oven spring the rapid final rise in the first minutes of baking, before the crust sets.
Scoring slashing the top of the loaf just before baking so it expands in a controlled way.
Crumb the interior texture of the loaf; "open crumb" means large, irregular holes.
Over-proofing letting the dough ferment too long so it loses strength and rise.
Float test dropping a spoonful of starter in water; if it floats, it's gassy and likely ready to bake with.
