A snack is a small portion of food generally eaten between meals. A snack is often less than 200 calories, but this can vary. Snacks come in a variety of forms including packaged snack foods and other processed foods, as well as items made from fresh ingredients at home.

Eating is the ingestion of food. In biology, this is typically done to provide a heterotrophic organism with energy and nutrients and to allow for growth. Animals and other heterotrophs must eat in order to survive — carnivores eat other animals, herbivores eat plants, omnivores consume a mixture of both plant and animal matter, and detritivores eat detritus. Fungi digest organic matter outside their bodies as opposed to animals that digest their food inside their bodies.