Some have been replaced by synthetic materials, whereas others have not been. In the plant, resins are actively synthesized and secreted into specialized canals or ducts. They probably are involved in wound responses or in limiting herbivory to the plants. In contrast to gums, resins are insoluble in water. One of the most ancient uses of resins was as part of incense.
Most resins are hydrocarbon-like and burn.
The value of these in the time of Christ is illustrated by the fact that the wise men brought these as gifts along with gold. They were early products of trade. They are removed as drops from the trees. Neither is especially valuable today. Many of these resins were also used for embalming by the Egyptians.