Silicones are inert, synthetic compounds with a variety of forms and uses. Typically heat-resistant and rubber-like, they are used in sealants, adhesives, lubricants, medical applications (e.g., breast implants), cookware, and insulation.

Silicones are polymers that include silicon together with carbon, hydrogen, oxygen, and sometimes other chemical elements. Some common forms include silicone oil, silicone grease, silicone rubber, and silicone resin.

Some of the most useful properties of silicones include:

Silicones have excellent resistance to oxygen, ozone, and ultraviolet (UV) light. This property has led to widespread use of silicones in the construction industry (e.g. coatings, fire protection, glazing seals) and the automotive industry (external gaskets, external trim).

They have high gas permeability: at room temperature (25 °C), the permeability of silicone rubber for such gases as oxygen is approximately 400 times^{[citation needed]} that of butyl rubber, making silicone useful for medical applications in which increased aeration is desired. However, silicone rubbers cannot be used where gas-tight seals are necessary.