Yams are tropical tuber crops. They are mainly cylindrical in shape, with rounded ends. The bark is mostly light brown when harvested and darkens during storage. They are a major staple in Nigeria. There are many varieties of yams but the most common are white yam (which is also referred to as the sweet yam), the yellow yam and the water yam. Yams are mostly popular because they are used to prepare a wide variety of quick recipes.