[size=75]From Wikipedia, the free encyclopedia [/size]
The common oat plant (Avena sativa) is a species of cereal grain grown for its seed, which is known by the same name (usually in the plural, unlike other grains). While oats are suitable for human consumption as oatmeal and rolled oats, one of the most common uses is as livestock feed. Oats make up a large part of the diet of horses and are regularly fed to cattle as well. Oats are also used in some brands of dog and chicken feed.
The wild ancestor of Avena sativa and the closely-related minor crop, A. byzantina, is the hexaploid wild oat A. sterilis. Genetic evidence shows that the ancestral forms of A. sterilis grow in the Fertile Crescent of the Near East. Domesticated oats appear relatively late, and far from the Near East, in Bronze Age Europe. Oats, like rye, are usually considered a secondary crop, i.e. derived from a weed of the primary cereal domesticates wheat and barley. As these cereals spread westwards into cooler, wetter areas, this may have favoured the oat weed component, leading to its eventual domestication. 
Oats are grown throughout the temperate zones. They have a lower summer heat requirement and greater tolerance of rain than other cereals like wheat, rye or barley, so are particularly important in areas with cool, wet summers such as Northwest Europe, even being grown successfully in Iceland. Oats are an annual plant, and can be planted either in autumn (for late summer harvest) or in the spring (for early autumn harvest).
Historical attitudes towards oats vary. Oat bread was first manufactured in England, where the first oat bread factory was established in 1899. In Scotland they were, and still are, held in high esteem, as a mainstay of the national diet. A traditional saying in England is that “oats are only fit to be fed to horses and Scotsmen”, to which the Scottish riposte is “and England has the finest horses, and Scotland the finest men”. Samuel Johnson notoriously defined oats in his Dictionary as “a grain, which in England is generally given to horses, but in Scotland supports the people”. Given the centrality of oats in traditional Scottish cuisine, it is not surprising that in Scotland the word “corn”, when otherwise unqualified, refers to oats, just as in England it refers to wheat and in North America and Australia, to maize. Oats grown in Scotland command a premium price throughout the United Kingdom as a result of these traditions.
Oats have numerous uses in food; most commonly, they are rolled or crushed into oatmeal, or ground into fine oat flour. Oatmeal is chiefly eaten as porridge, but may also used in a variety of baked goods, such as oatcakes, oatmeal cookies, and oat bread. Oats are also an ingredient in many cold cereals, in particular muesli and granola. Oats may also be consumed raw, and cookies with raw oats are becoming popular.
Oats are also occasionally used in Britain for brewing beer. Oatmeal stout is one variety brewed using a percentage of oats for the wort. The more rarely used Oat Malt is produced by the Thomas Fawcett & Sons Maltings and was used in the Maclay Oat Malt Stout before Maclay ceased independent brewing operations.