A Dutch oven is a cast iron pot that comes with bare cast iron or enameled cast iron as the image below. These can not only be used for cooking but also for advanced bread baking.
Cast iron Dutch ovens conducts heat evenly for consistent baking, and has a heavy lid that traps any steam released by the bread while it cooks. Steam is useful because it keeps the outside of your loaf from setting before the bread rises, drying out, or baking too quickly. You don’t want to burn your crust while you wait for the center of the bread to cook!
By slowing down crust formation, steam helps the bread rise rapidly without the constraint of a stiff crust when it hits the oven, known as “oven spring”, keeps the outer crust thin and crispy rather than tough and chewy, and lets bread develop a deep brown color without burning.