Manioc is also known as cassava or yuca and can basically be compared to a potato. It is a starchy root vegetable that is widely used in South America, specially for baking and cooking. It is a significant source of carbs and provides a small amount of fiber, vitamins and minerals.
The most commonly consumed part is the root, which is super versatile. It has a thick brown skin and the pulp inside is white or sometimes yellowish. It can be eaten whole, grated or ground into flour to make delicious (gluten free) baked goods. But it has to be cooked before eaten. Also, the root is well known as the raw material that's used to produce tapioca.
Manioc is grown in tropical regions because it is able to withstand difficult growing conditions - in fact, it's one of the most drought-tolerant crops.