Farnesol is a natural 15-carbon organic compound which is an acyclic sesquiterpene alcohol. Under standard conditions it is a colorless liquid. It is hydrophobic, and thus insoluble in water, but miscible with oils.

Farnesol is produced from 5-carbon isoprene compounds in both plants and animals. Phosphate activated derivatives of farnesol are the building blocks of most, and possibly all, acyclic sesquiterpenoids. These compounds are doubled to form 30-carbon squalene, which in turn is the precursors for steroids in plants, animals, and fungi. As such, farnesol and its derivatives are important starting compounds for both natural and artificial organic synthesis.

Farnesol is present in many essential oils such as citronella, neroli, cyclamen, lemon grass, tuberose, rose,musk, balsam and tolu. It is used in perfumery to emphasize the odors of sweet floral perfumes. Its method of action for enhancing perfume scent is as a co-solvent that regulates the volatility of the odorants. It is especially used in lilac perfumes.