Used primarily in photography as a developing agent for black-and-white films and papers, it helps in reducing silver halides to metallic silver, creating the final image. In the field of chemistry, it serves as a reagent for detecting dissolved oxygen in water, where it reacts to form a colored compound indicating oxygen levels. Additionally, it is employed in the synthesis of certain dyes, pharmaceuticals, and cosmetics such as hair dyes, leveraging its reducing and durable staining properties. In dermatology, it has been historically used in topical treatments for skin conditions like psoriasis and warts, although its use has declined due to safety concerns. It also finds application in gas analysis for absorbing oxygen, ensuring accurate measurements in laboratory settings, and as an antioxidant in biological studies to prevent oxidation of samples.