What is "sub"?

A sub, short for submarine sandwich, is a type of sandwich that is made on a long, cylindrical roll that is typically made from Italian or French bread. The roll is sliced lengthwise and filled with a variety of meats, cheeses, vegetables, and condiments, such as lettuce, tomato, onion, mayonnaise, mustard, and oil and vinegar dressing. Common meats used for a sub include ham, turkey, roast beef, salami, and chicken, while cheeses can range from provolone to American. The sandwich is often served cold, but can also be heated in an oven or on a griddle to melt the cheese and warm the meat. Subs are a popular food item in many countries around the world, and are available at delis, sandwich shops, and fast food restaurants.