Frankincense is a pleasant smelling gum resin of the genus boswellia.
In Biblical times, when even roll-on deodorant had yet to be invented, it was much sought after and fortunes were to made by bringing it from Somalia or Arabia to sell to smelly Israelites.
It also had a ceremonial, symbolic role.
It was used as an offering to God [Leviticus 2:1-2] and was one of the gifts brought to Jesus by the three wise men [Matthew 2:11].
Not to be confused with the monster creator with a similar name.