Walnuts are a type of tree nut that come from the walnut tree, which is native to regions of Central Asia, Europe, and North America. They have a hard, woody shell that encases a single edible kernel or seed. The kernel is divided into two lobes that are covered by a thin, brown skin.

Walnuts are known for their distinctively rich, nutty flavor and buttery texture. They are a good source of healthy fats, including omega-3 fatty acids, and contain protein, fiber, vitamins, and minerals such as magnesium and phosphorus.

There are several varieties of walnuts, including English or Persian walnuts, which are the most commonly consumed type in the United States, as well as black walnuts, which have a stronger, more earthy flavor. Walnuts can be eaten raw or roasted, and are used in a variety of sweet and savory dishes, such as baked goods, salads, and sauces. They can also be used to make walnut oil, which is often used in cooking and as a salad dressing.