Used as an antidote for cyanide poisoning, administered intravenously to convert cyanide into less toxic thiocyanate. Commonly employed in emergency medicine and industrial poisoning cases. Also used in water treatment to remove chlorine and chloramine residues, especially in aquariums and wastewater systems. Applied in photographic processing to fix images by dissolving unexposed silver halides. Utilized in analytical chemistry for iodometric titrations to determine oxidizing agents. Employed in dermatology to treat certain skin conditions like pityriasis versicolor. Used in agriculture and aquaculture to reduce chlorine toxicity in fish and plants.