Navel oranges are a type of citrus fruit that are characterized by their distinctive navel-like shape at the stem end. They are named for their resemblance to a human navel, and are also known as 'belly button oranges'. Navel oranges are seedless and have a sweet flavor, making them popular for eating out of hand or juicing. They are also used in baking and cooking, and are a common ingredient in marmalade.