Frankincense essential oil, also known as olibanum and boswellia, is a milky white sap that runs from the cut bark of Boswellia trees. It is allowed to harden for a few days before the teardrop-shaped resinous beads are scraped off the tree. The oil has a woody, spicy and slightly fruity aroma and is used in aromatherapy, wellness, and perfumery.