Silicones, or "polysiloxanes", are inorganic polymers consisting of a silicon-oxygen backbone (...-Si-O-Si-O-Si-O-...) with side groups attached to the silicon atoms. Certain organic side groups can be used to link two or more of these -Si-O- backbones together. By varying the -Si-O- chain lengths, side groups, and crosslinking, silicones can be synthesized into a wide variety of materials. They can vary in consistency from liquid to gel to rubber. The most common type is linear polydimethylsiloxane or PDMS. The second largest group of silicone materials are based on silicone resins which are formed by branched and cage-like oligosiloxanes.
Silicones are odorless, colorless, water resistant, chemical resistant, oxidation resistant, stable at high temperature, and do not conduct electricity. They have many uses, such as lubricants, adhesives, sealants , gaskets, breast implants, pressure compensating diaphragms for drip irrigation emitters, sex toys, and Silly Putty. An enormous controversy developed during the 1990s around concerns that the silicones in breast implants were responsible for several diseases. Health concerns included pain, deformity and the less obviously related connective tissue disorders (eg. scleroderma, arthritis) and chronic fatigue syndrome. Leakage of silicone from implants could be demonstrated easily but proof of its safety or otherwise was lacking. The Dow Corning corporation settled several class actions globally before good evidence emerged clearing silicone of causing connective tissue disease. Silicone implants have been removed from the market in some countries (notably the US) because of the 'Silicone Controversy' but are extensively used elsewhere.
Silicone is often mistaken colloquially for elemental silicon, because of the similarity in pronunciation and spelling, but they are entirely different. For example, in the Shakira song "Objection (Tango)", the lyrics "next to her cheap silicon I look minimal" should be "next to her cheap silicone I look minimal."