A tuna fish sandwich, also known as a tuna salad sandwich or a tuna sandwich, is a sandwich made from canned tuna—usually made into a tuna salad by adding mayonnaise, and sometimes other ingredients such as celery or onion—as well as other common fruits and vegetables used to flavor sandwiches. It is commonly served on sliced bread. Variations include the tuna boat (served on a bun or roll) and the tuna melt (served with melted cheese). The more general term of tuna sandwich may also refer to cuisine utilizing filet of raw or cooked tuna, rather than canned tuna.