Natural resin is a sticky substance produced by certain trees and plants, primarily as a defense mechanism against injury or infection. It is composed of organic compounds and can harden when exposed to air, forming a solid material. Common sources of natural resin include pine and fir trees, which release resin when their bark is damaged. Natural resins have been used for various purposes throughout history, including in the production of varnishes, adhesives, and incense. They are also important in traditional medicine and are sometimes used in the creation of jewelry and art. Their unique properties make them valuable in both industrial and artistic applications.