Oats are a whole-grain food, known scientifically as Avena sativa. Oat groats, the most intact and whole form of oats, take a long time to cook. For this reason, most people prefer rolled, crushed or steel-cut oats. Instant (quick) oats are the most highly processed variety. While they take the shortest time to cook, the texture may be mushy.
Oats are commonly eaten for breakfast as oatmeal, which is made by boiling oats in water or milk. Oatmeal is often referred to as porridge. They're also often included in muffins, granola bars, cookies and other baked goods.
