Avena is a genus of Eurasian and African plants in the grass family. Collectively known as the oats, they include some species which have been cultivated for thousands of years as a food source for humans and livestock. They are widespread throughout Europe, Asia and northwest Africa. Several species have become naturalized in many parts of the world, and are regarded as invasive weeds where they compete with crop production. All oats have edible seeds, though they are small and hard to harvest in most species.

The oat, sometimes called the common oat, is a species of cereal grain grown for its seed, which is known by the same name. Oats are used for human consumption as oatmeal, including as steel cut oats or rolled oats. They appear to have been domesticated as a secondary crop as their seeds resembled those of other cereals closely enough for them to be included by early cultivators. Oats are a nutrient-rich food associated with lower blood cholesterol and reduced risk of human heart disease when consumed regularly. One of the most common uses of oats is as livestock feed; the crop can also be grown as groundcover and ploughed in as a green manure.