Grape-Nuts is a brand of breakfast cereal made from flour, salt and dried yeast, developed in 1897 by C. W. Post, a former patient and later competitor of the 19th-century breakfast food innovator Dr. John Harvey Kellogg. Post's original product was baked as a rigid sheet, then broken into pieces and run through a coffee grinder.

Breakfast cereal is a breakfast food made from processed cereal grains. It is traditionally eaten as part of breakfast, or a snack food, primarily in Western societies.