A walnut is a type of nut that comes from a tree in the genus Juglans. It has a hard, brown shell that covers a white, edible kernel. The kernel is usually divided into two halves by a thin membrane. Walnuts are rich in omega-3 fatty acids, antioxidants, and other nutrients that may benefit your health. Walnuts are commonly eaten raw, roasted, or chopped and added to salads, desserts, or baked goods. They can also be used to make walnut oil, butter, or milk. Walnuts have a mild, nutty flavor and a crunchy texture.