Terpenoids of different sizes and composition are found in all classes of living things, and are the largest group of natural products. Plant terpenoids are extensively used for their aromatic qualities. Terpenoids contribute to the scent of eucalyptus, the flavors of cinnamon, cloves and ginger and the color of yellow flowers. They play a role in traditional herbal remedies and are under investigation for antibacterial, antineoplastic and other pharmaceutical effects.