A kumquat is a small, citrus fruit that is oval-shaped and typically the size of a large grape. Unlike other citrus fruits, the skin of a kumquat is edible and sweet, while the inside flesh is tart. Kumquats are often eaten whole, including the skin, and can be used in salads, desserts, or as a garnish. They are native to China, but are now grown in other subtropical regions around the world. Kumquats are a good source of vitamin C, fiber, and antioxidants, and may have health benefits such as improved digestion and immune function.