Bitter orange, also known as Citrus aurantium, is a fruit that is native to Southeast Asia. It is characterized by its small size, bright orange color, and a distinctively tart flavor. The fruit is often used in culinary applications, particularly in marmalades and liqueurs, such as Grand Marnier. The tree that produces bitter orange is also valued for its fragrant flowers, which are used to make neroli oil and orange blossom water. Additionally, the fruit's peel contains essential oils that are utilized in aromatherapy and natural remedies. Bitter orange is sometimes used in weight loss supplements due to its active compound, synephrine.