Natural rubber is an elastic polymer, with a physical appearance of milky emulsion (known as latex-sap of different plants and trees, mainly from Heveas).
Nowadays Heveas are cultivated in big plantations. In some cases these plantations are property of big tyre companies. The biggest production area is the Asian Southeast. There used to be plantations also in tropical Africa, Guinea, Liberia and Congo.
In the beginning of XVIIIth century, it was discovered that natural rubber was formed by hydrocarbon chains, and here started the possibility of producing Synthetic rubber.