Natural rubber is an elastomer (elastic hydrocarbon polymer), that is made from latex, which is a milky colloid obtained from many plants. An elastomer is a substance which can undergo much more elastic deformation under stress than most materials and still retain its previous size without any deformation. The commercial source of natural rubber is the native Brazilian plant, Hevea brasiliensis, which belongs to the family, Euphorbiaceae. Some other plants from which natural rubber is made are gutta-percha, rubber fig, Panama rubber tree, common dandelion and Russian dandelion. Natural rubber has been in commercial use since the early 20th century. Natural rubber occupies an important place in the market due to its large number of applications. Some of its applications include making tires used on racing cars, trucks, buses, and airplanes. Synthetic rubbers are made in chemical plants by polymerization of monomers into polymers. They are artificially produced. Some of the most important synthetic rubbers are butadiene, styrene-butadiene, neoprene/ polychloroprene, polysulfide rubbers, nitrile, butyl rubber, and silicone. They have various applications and varying chemical and mechanical properties. Many synthetic rubbers have been developed during the 20th century. Some of them are used in place of natural rubber due to their properties. Typical applications include power transformers, wet-suits, laptop sleeves, orthopedic braces, electrical insulation, automotive fan belts, vehicle tires, shoe soles, pencil erasers, birthday balloons, adhesives, protective gloves, conveyor belts, flexible toys, tubing, mats, rubber bands, paint, hoses, gaskets, and floor tiles. Natural rubber has an important position in the market due to its applications. However, synthetic rubber is used in place of natural rubber in many cases, particularly when improved material properties are necessary.