The word cereal means edible grains. Cereal includes everything from a grain of wheat right off the stalk to a bowl of multicolored, processed, and puffed shapes with marshmallows added.
Wheat, rice, and corn are common cereal grains. All of these can be prepared many different ways to make breakfast cereal.
Oatmeal is an example of the simplest and most nutritious kind of breakfast cereal. Old-fashioned oatmeal, the kind that you cook for five minutes before eating, is simply rolled oats. Oat grains are steamed to soften them; then they are rolled flat. That's it. Quick cooking oats, the one-minute kind, are cut into small pieces before they are rolled. Instant oatmeal - the kind you add hot water to and it's ready to eat - is precooked.
Getting a little more complicated and a little less nutritious, we have flake cereals like corn flakes and raisin bran. Corn flakes, raisin bran, and other processed cereals have more than one ingredient. The ingredients listed on a box of corn flakes include corn, sugar, corn syrup, flavoring, salt, and vitamins. There are more steps to making corn flakes, too. First, corn grits are cooked in a pressure cooker to soften. Then they are piped into hot air dryers. Next, the grits pass between large rollers to flatten them. In the next step, they are toasted as they pass quickly through a huge oven. Finally, vitamins and minerals are sprayed on the flakes.