A hamburger (or cheeseburger when served with a slice of cheese) is a sandwich consisting of one or more cooked patties of ground meat, usually beef, placed inside a sliced bread roll or bun. Hamburgers may be cooked in a variety of ways, including pan-frying, barbecuing, and flame-broiling. Hamburgers are often served with cheese, lettuce, tomato, bacon, onion, pickles, and condiments such as mustard, mayonnaise, ketchup, relish, and chiles.