Chowder is a thick soup prepared with milk or cream, a roux, and seafood or vegetables. Oyster crackers or saltines may accompany chowders as a side item, and cracker pieces may be dropped atop the dish. New England clam chowder is typically made with chopped clams and diced potatoes, in a mixed cream and milk base, often with a small amount of butter. Other common chowders include seafood chowder, which often consists of fish, clams, and other types of shellfish; lamb or veal chowder made with barley; corn chowder, which uses corn instead of clams; various fish chowders; and potato chowder, which is often made with cheese. Fish, corn, and clam chowders are popular in North America, especially Atlantic Canada and New England.

Roux is a mixture of flour and fat cooked together and used to thicken sauces. Roux is typically made from equal parts of flour and fat by weight. The flour is added to the melted fat or oil on the stove top, blended until smooth, and cooked to the desired level of brownness. A roux can be white, blond (darker) or brown. Butter, bacon drippings or lard are commonly used fats. Roux is used as a thickening agent for gravy, sauces, soups and stews. It provides the base for a dish, and other ingredients are added after the roux is complete.