Facts from Wikipedia and The World’s Healthiest Foods
Kale freezes well and actually tastes sweeter and tastier after being exposed to a frost.
Kale is a form of Cabbage in which the central leaves do not form a head.
In Scotland, kale provided such a base for a traditional diet that the word in dialect Scots is synonymous with food. To be “off one’s kail” is to feel too ill to eat.

Kale is a very good source of iron, calcium, vitamin C, Folic Acid, vitamin K and Carotenoids (which provide vitamin A).
Curly kale played an important role in early European foodways, having been a significant crop during ancient Roman times and a popular vegetable eaten by peasants in the Middle Ages.
How to select and store
Look for firm Kale that is dark green and unwilted. Choose smaller leaves because they are more tender. Once home store unwashed in a damp paper towl. Wash only when you are ready to eat. Kale is best in the winter months and early spring.