A snack is a portion of food

Food

Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...

 oftentimes smaller than that of a regular meal, that is generally eaten between meals. Snacks come in a variety of forms including packaged and processed foods and items made from fresh ingredients at home.

Traditionally, snacks were prepared from ingredients commonly available in the home. Often leftovers, sandwiches made from cold cuts, nuts, fruit, and the like were used as snacks.