Resin in the most specific use of the term is a hydrocarbon secretion of many plants, particularly coniferous trees. Resins are valued for their chemical properties and associated uses, such as the production of varnishes, adhesives, and food glazing agents; as an important source of raw materials for organic synthesis; and as constituents of incense and perfume. Plant resins have a very long history that was documented in ancient Greece by Theophrastus, in ancient Rome by Pliny the Elder, and especially in the resins known as frankincense and myrrh, prized in ancient Egypt. These were highly prized substances, and required as incense in some religious rites. Amber is a hard fossilized resin from ancient trees. More broadly, the term "resin" also encompasses a great many synthetic substances of similar mechanical properties (thick liquids that harden into transparent solids), as well as shellacs of insects of the superfamily Coccoidea.
Contributions by Old Moonraker, Just plain Bill, and Edgar181.