Oats are an annual grass belonging to the genus Avena. They have been around for a long time but were considered, by the early civilizations, to be a harmless weed growing among the barley. Oats were not cultivated, per se, until much later.
A sea captain introduced oats to North America in the 1600's and it was grown mostly for horse feed and bedding. Oat kernels are similar to wheat but the bran covering the oat kernel is softer so it stays "glued" to the germ. Like with all cereals, the less processed, the better for you. But oats have a unique advantage over other cereals : they contain a soluble fiber which helps lower cholesterol. Also the pericarp in oats contains elements with soothing, antispasmodic, and anti-inflammatoryproperties.
Now to clear some oat terms:
Oat groats are the oats with only the outer husk removed. Steel cut oats are rougher than rolled oats and take a good 30 minutes to cook.
Old fashioned rolled oats are the groats which are steamed and then flattened with a roller.
Oat flour is made by grinding the rolled oats in a food processor.
Oats in one form or another are a favorite ingredient in breads, cookies and bars, over fruit crumbles or in muesli; in hearty soups or as a stick-to-the-ribs breakfast cereal.