Frankincense oil is distilled from the resin of the Olibanum tree. This resin has been used as incense and perfume for millenia. It has a warm scent and is believed to be very good for the skin, as well as a variety of physical ailments. The tree is "wounded" (slashed wth a knife), which produces the resin (which heals and seals the "wound"). The resin, known as "tears", is then collected and cured for use.
Frankincense also has a very long history of use in the spiritual realm. It was notably given to Jesus as a gift from the Magi (or the Three Wise Men). Frankincense has been used for centuries around the world: in Africa, India, and Europe and was once considered a very valuable commodity in trade.