A kumquat is a small citrus fruit about the size of a large olive or grape, with one surprising difference from other citrus fruits: you eat the whole thing, peel and all. The peel is sweet while the inside is tart, so when you bite into a kumquat, you get both flavors at once.

Kumquats originally came from China, where they've been grown for thousands of years. They look like tiny oranges, usually oval or round, and grow on small trees or bushes. Unlike an orange or lemon, where you peel away the skin to eat the fruit inside, a kumquat's thin peel is actually the sweetest part. The flesh inside tastes sour, almost like a lemon. When you eat them together, the sweet and sour balance each other out.

People eat kumquats fresh as snacks, slice them into salads, or cook them into marmalades and desserts. Some people like to roll them between their hands before eating to mix the flavors even more.