Roux
Roux () is 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. Butter, vegetable oils, 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.
Gumbo
Gumbo is usually identified by its dark roux, cooked until it is a color "a few shades from burning". The roux is used with okra or filé powder. Seafood is popular in gumbo the closer to the water the people are, but the southwestern areas of Louisiana often use fowl, such as chicken or duck, and sausage. The fowl is generally not deboned, and onions, celery, and bell pepper are not strained out of the dish. Cajun gumbo is usually topped with parsley and green onions.