Aerogel is an "ultralight, low-density synthetic porous material" where the liquid in a gel is replaced by gas without collapsing its structure, resulting in a solid that is up to 99.8% air. Also known as "frozen smoke" or "solid cloud".  Aerogel insulation is applied in construction for ultra-thin wall, roof, and window insulation; in industry for pipelines, tanks, and industrial equipment to save energy and improve safety; and in aerospace, automotive, and cryogenic systems to protect against extreme temperatures. It is also used in energy storage systems to prevent thermal runaway in EV batteries, as well as in specialized clothing and electronics.