The term “leftovers” is used collectively to refer to food which is left over after a meal. At home, many cooks deliberately plan for leftovers so that they can be integrated into other dishes or eaten on their own. When eating out, some people end up with leftovers due to generous portions, and they may take them home to snack on later. Many people are familiar with leftovers, along with an assortment of creative ways for using leftover food.

Many home cooks like to generate leftovers to make cooking easier. For example, a cook could roast a whole chicken, creating a large volume of leftovers which could be used to make chicken soup, chicken casserole, and an assortment of other dishes. A cook might also generate leftovers for the purpose of packing them for lunch on the following day, or so that food will be ready at home after a long day of work. Leftovers can also be repurposed into entirely new meals.

In some households, people hold a “leftover night” in which family members attempt to use up all of the leftovers remaining from the previous week. Leftover nights are useful because they ensure that everyone eats dinner without having to make an effort, and they use up food which could otherwise go bad. Some leftovers have a sacred place in the food pantheon; in the United States, for example, Thanksgiving leftovers like cranberry sauce, turkey, mashed potatoes, and stuffing are very popular.

In restaurant situations, leftovers are less common, but they certainly occur. In some instances someone may actually deliberately over-order for the purpose of having leftovers. Many restaurants package their leftovers in a “doggie bag,” in a reference to canine friends at home who might enjoy snacking on leftover bones. A doggie bag may also be called a to-go bag or box, or simply a box.

There are some food safety concerns with leftovers which should be considered when packaging and reusing leftovers. Leaving food out can invite bacteria, so it is important to package and refrigerate leftovers as quickly as possible to keep them sanitary. It is also a good idea to heat leftovers very thoroughly, as a full heating will kill unwanted visitors. Finally, cooking food doesn't prevent it from going bad; most leftovers have a shelf life of a few days to a week, and if you are in doubt, you should discard your leftovers rather than risking food borne illness.