A chili dog is a hot dog served in a bun and topped with a meat sauce, usually chili con carne. Additional toppings may include cheese, onions, and mustard. The style has multiple regional variations in the United States, many calling for specific and unique sauce ingredients, types of hot dogs, or types of buns, and referred to regionally under region-specific names. It is commonly served as a casual food in settings such as diners, fast-food establishments, and sporting events