Rolled oats are a type of lightly processed whole-grain food. Traditionally, they are made from oat groats that have been dehusked and steamed, before being rolled into flat flakes under heavy rollers and then stabilized by being lightly toasted.
Thick-rolled oats are large whole flakes, and thin-rolled oats are smaller, fragmented flakes. Rolled whole oats, without further processing, can be cooked into a porridge and eaten as old-fashioned oats or Scottish oats, but more highly fragmented and processed rolled oats absorb water much more easily and therefore cook faster into a porridge, so they are sometimes called "quick" or "instant" oats.
Besides porridge, rolled oats are most often the main ingredient in granola and muesli. They can be further processed into a coarse powder, which, when cooked, becomes a thick liquid like broth. Finer oatmeal powder is often used as baby food.