A heavy, lidded pot (usually cast iron) used to bake sourdough -- it traps steam from the dough to create a crispy crust and good oven spring.
The Dutch oven solves the home baker's biggest challenge: generating enough steam. Professional ovens have steam injection, but home ovens don't. By baking in a sealed Dutch oven, the moisture released from the dough stays trapped, keeping the crust flexible during the first 20 minutes of baking and allowing maximum oven spring. After removing the lid, the crust dries out and crisps up. Preheat your Dutch oven before baking for best results.