Used as a highly effective surfactant in fire-fighting foams, especially in aqueous film-forming foams (AFFF) for suppressing flammable liquid fires. Its strong surface activity and thermal stability make it ideal for forming a protective film that prevents fuel vapor release and extinguishes flames quickly. Also applied in metal plating processes to improve surface finish and reduce defects. Historically used in some industrial coatings and cleaning products for its ability to lower surface tension in harsh conditions. Due to environmental persistence and toxicity concerns, its use has been largely phased out in many regions.