Silicon is the second most common element in the Earth's crust. Silicones are polymeric organosilicon compounds containing Si-O-Si linkages and Si-C bonds. They have many useful properties including low conductivity, thermal stability, chemical inertness, and resistance to oxygen, ozone, and UV light. Silicones have various applications including use in textiles as coatings and softeners, in medicine as elastomers for devices like catheters, and in plants and human health where silicon plays a role in photosynthesis, stress resistance, and bone/tissue health.