Yams are the starchy underground tubers of the genus Dioscorea, staple food across West Africa, the Caribbean, and the Pacific, where they sustain hundreds of millions of people. They provide good potassium and zinc but little vitamin C, while yellow-fleshed types add carotenes. They are cooked like potatoes — boiled, roasted, fried, or pounded into fufu — and sometimes milled into flour. Shoppers should not confuse them with North American sweet potatoes, which are often mislabelled as yams but belong to a different family entirely. Firm texture and long keeping at ambient temperature make them a dependable staple crop.