Tree resins are sticky substances produced by various types of trees, primarily as a defense mechanism against injury or infection. These natural compounds can be found in trees like pine, fir, and cedar. When a tree is damaged, it secretes resin to seal wounds and protect itself from pests and pathogens. Resins have been used by humans for thousands of years for various purposes, including making incense, varnishes, and adhesives. Some resins, such as amber, are fossilized and can be found in jewelry and decorative items. Others, like copal, are still harvested for their aromatic properties and used in traditional rituals.