A snack food (commonly called a snack) is seen in Western culture as a type of food not meant to be eaten as a main meal of the day – breakfast, lunch, or dinner – but one rather that is intended to assuage a person's hunger between these meals, providing a brief supply of energy for the body. The term may also refer to a food item consumed between meals purely for the enjoyment of its taste.

Traditionally snacks were prepared from ingredients commonly available in the home, often leftovers, sandwiches made from cold cuts, nuts, fruit, and the like. The Dagwood sandwich was originally the humorous result of a cartoon character's desire for large snacks.

With the multiplication of convenience stores, packaged snack foods are now a significant business. Snack foods are typically designed to be portable, quick and satisfying. Processed snack foods are designed to be less perishable, more durable, and/or more appealing than prepared foods. They often contain substantial amounts of sweeteners, preservatives, and appealing ingredients such as chocolate, peanuts, and specially designed flavors (such as flavored potato chips). A snack eaten shortly before going to bed or during the night may be called a midnight snack.