Sodium thiosulfate is a chemical compound with the formula Na2S2O3. It appears as a white crystalline powder and is commonly used in various applications, including photography, where it acts as a fixer to remove unexposed silver halides from film. It is also utilized in water treatment to neutralize chlorine and in medicine as an antidote for cyanide poisoning. In addition to its industrial uses, sodium thiosulfate plays a role in laboratory settings for titrations and as a reagent in chemical analysis. It is soluble in water, making it easy to work with in solutions. Safety precautions should be taken when handling this compound, as it can cause irritation.