Raw rubber is a polymer, occurring in the milk juice of a number of plants, and characterized by a high elasticity. Columbus was the first European to mention it, but it took until 1735 before rubber was introduced into Europe. Only after 1839, when vulcanising was discovered, did rubber become an important article. In vulcanising, raw rubber is heated with sulphur, resulting in a stronger elastic product which is temperature proof as well, an ideal combination for tires. With the growing automobile industry the need for rubber increased tremendously and this led to the development of large plantations in Malaysia and Indonesia (Rubber producing plants 1, Rubber producing plants 2). However, when the supply of rubber was cut off during the Second World War, the search for synthetic products was started, and today twice as much synthetic rubber as natural rubber is produced.
The most important producers of natural rubber are para rubber, Hevea brasiliensis, yielding almost 99%; Panama rubber, Castilloa elastica, an earlier source of natural rubber lost its position to the para rubber because of lower yields; and India rubber, Ficus elastica (see Ficus carica), also an early source of rubber replaced by para rubber.

Guttapercha, Palaquium gutta, see Achras zapota, is less elastic and was used for the insulation of undersea cables and in golf balls. The sapodilla, Achras zapota, produces ‘chickle’, which is used in chewing gum and was already known by the Aztecs.