What is a "Seville orange"?

The Seville orange, also known as bitter orange or sour orange, is a citrus fruit widely cultivated in Mediterranean regions. It is named after Seville, Spain, where it was historically grown. Seville oranges are medium-sized with a rough, thick, and bumpy skin that ranges in color from bright orange to yellow-orange. They are known for their extremely tart and bitter flavor, which makes them unsuitable for eating raw but ideal for culinary uses. Seville oranges are commonly used in cooking, particularly for making marmalades, sauces, and flavorings.