On this Wikipedia the language links are at the top of the page across from the article title. The oat grains are de-husked by impact, and are then heated and cooled to oatmeal cups the groats, the seed inside the husk. The groats may be milled to produce fine, medium, or coarse oatmeal. Rolled oats are steamed and flattened whole oat groats.

Old-fashioned oats may be thick and require longer cooking time. Quick-cooking rolled oats are cut into small pieces before being steamed and rolled. Instant oatmeal is cooked and dried, often with a sweetener and flavorings added. Percentages are roughly approximated using US recommendations for adults. Both types of rolled oats may be eaten uncooked, as in muesli, or may be cooked with water or milk to make porridge.

In some countries, rolled oats are eaten raw or toasted with milk and sugar, sometimes with raisins added, as in muesli. The term ‘oatmeal’ sometimes refers to a porridge made from the bran or fibrous husk as well as from the kernel or groat. It could be flavoured with cream, sugar, butter, salt, honey, seeds or fruit on top. Because of its cheapness, and the ease with which it could be prepared in large quantities, stirabout was widely served in institutions like prisons, boarding schools, convents and workhouses. Oatmeal has a long history in Scottish culinary tradition because oats are better suited than wheat to the country’s low temperatures and high humidity.