is a type of silicone, often used in  cosmetics, personal care products, and  

certain medical applications. Its main function  is as a conditioner, delivery agent, lubricant,  

and solvent, providing a silky, smooth feel when  applied to the skin or hair. Its low surface  

tension allows it to spread easily and fill in  fine lines or wrinkles. The substance is volatile,  

meaning it evaporates quickly, leaving behind  no residue or build-up. Despite these benefits,  

there are concerns about its environmental  impact. While generally considered safe for  

human use, it's non-biodegradable  and persistent in the environment,  

which has led to regulatory scrutiny  and calls for alternatives. It's still  

widely used, but manufacturers are  exploring more sustainable options.