A tuna sandwich is a classic lunchtime favorite. It consists of two slices of bread, usually white or wheat, with tuna salad in the middle. The tuna salad is usually made with canned tuna, mayonnaise, and other ingredients such as celery, onion, and pickles. The sandwich can be served cold or hot, depending on preference. Melts are a variation of the tuna sandwich where the sandwich is heated and cheese is added to the top slice of bread. This creates a warm, gooey, and delicious sandwich.