Kale is a dark green leaf vegetable. The common kind has thick, curly leaves; some other kinds have flatter, longer leaves, but they are still kale, not a different plant in the kitchen. It belongs with cabbage and the like: same old garden family, but you eat the leaves, not a round head. The taste is strong and a bit bitter, so people usually cook it, massage it in a salad, or blend it into a drink rather than eat a raw handful like lettuce. In the 2010s it became a fashionable “health food” in English-speaking countries, which is why you see it on café menus and in smoothie names. It is ordinary winter greens, not a magic food. In a shop it looks much darker and tougher than spinach.