Leftovers are the uneaten edible remains of a meal after the diner has finished eating. Food scraps that are not considered edible (such as bones or the skins of some vegetables and fruits) are not regarded as leftovers, but rather as waste material; any remaining edible portions constitute the leftovers.
The ultimate fate of leftovers depends on where the meal was eaten, the preferences of the diner, and the prevailing social culture. Home cooking leftovers are often saved to be eaten later. This is facilitated by being in a private environment, with food preserving facilities such as airtight containers and refrigeration close at hand. Some leftover food can be eaten cold from the refrigerator, while others may be reheated in a microwave or a conventional oven, or mixed with additional ingredients and recooked to make a new dish such as bubble and squeak.
New dishes made from leftovers are quite common in world cuisine, and many were created in the days before refrigeration and reliable airtight containers existed. Besides capturing nutrition from otherwise inedible bones, stocks and broths make an excellent base for adding leftover morsels too small to be a meal themselves. Casseroles, paella, fried rice, and pizza can also be used for this purpose, and may even have been invented as a means of reusing leftovers. Among American university students, leftover pizza itself has acquired particular in-group significance, to the extent that the USDA's Food Safety and Inspection Service offers, as its first tip under "Food Safety Tips for College Students, a discussion of the risks of eating unrefrigerated pizza, which are considerable
Leftovers from a restaurant meal may either be left behind to be discarded by the restaurant, or taken away by the diner for later consumption. In order to take the food away, the diner may make a request for it to be packaged. The container used for such leftovers is commonly called a doggie bag or doggy bag; the name comes from the euphemistic pretense that the food will be given to the diner's pet, rather than eaten by a person. Doggy bags are most common in restaurants that offer a take-out food service as well as sit-down meals, and their prevalence as an accepted social custom varies widely by location. In some countries people would frown upon a diner asking for a doggy bag.
Some cultures regard the leaving of some uneaten food by dining guests as a symbol of satisfaction with the meal, while others consider this to be rude. In some cultures, it is polite to leave a half-bite on the plate in the manner of a libation. It also serves the purpose of indicating that the food provided by the host was sufficient in quantity. Wiping one's plate clean can indicate the opposite (though can also be a sign of satisfaction with the meal), while leaving more food uneaten may be interpreted as a dislike to the food; both are potential signs of impoliteness to one's hosts.
At some holiday meals, such as Christmas in Western countries and Thanksgiving in the USA, it is customary for the host to prepare much more food than can be eaten, specifically in order to send leftovers home with the guests. Cold turkey is archetypal in the United States as a Thanksgiving leftover, with turkey meat often reappearing in sandwiches, soups, and casseroles for several days after the feast.
The word "ort", meaning a small scrap of food left after a meal is completed, is not commonly heard in conversation, but is frequently encountered in crossword puzzles.