A Dutch oven is a large, heavy casserole pan, most often made of enamel-covered cast iron. It has a tight fitting lid that holds in moisture, so it is primarily used for braising and stewing tough meats and vegetables. It can be used efficiently on the stovetop, but is more often used in the oven, where it holds and radiates the oven's heat evenly throughout the pot.
Often called for in the making of a stew or the cooking of a roast, a Dutch oven can be used to brown the meat on the stovetop before other ingredients are added. Then the lid is added and the dish is generally finished in the oven. The tight, heavy lid enhances condensation in the pot and also radiates heat into the pot, turning it into a snug oven that surrounds the food in moist heat.
The Dutch oven may also be called a stew pot or heavy casserole, and it may also be made of aluminum, stainless steel, copper, and uncoated cast iron. The enameled cast-iron pots are less likely to rust and easier to clean than the plain cast iron. They range in size from 3 quarts to 12 quarts, with most people opting for 6 to 9 quarts.
One source we have says the Dutch oven is of Pennsylvania Dutch heritage, dating from the 1700s.
The good ones are not inexpensive, but they will also outlast most other cookware. If you can afford to add another pot to your cooking arsenal, you should definitely have a good Dutch oven.