Dihydroxyacetone (DHA) is the simplest ketose sugar, a three-carbon compound with the molecular formula C3H6O3. It appears as a white, crystalline, hygroscopic powder that readily forms dimers in the solid state but exists primarily as the monomer in aqueous solution. DHA plays a key role in carbohydrate metabolism as an intermediate in the glycolysis pathway and is naturally present in plants and fermented foods. Its primary commercial application is in sunless tanning cosmetics, where it reacts via the Maillard reaction with amino acids in the skin's stratum corneum to form brown melanoidins, producing a temporary tan lasting 5-7 days. Chemically, it undergoes tautomerization to glyceraldehyde in solution and is used in biochemical research for studying ketose-aldose isomerization. DHA is also employed in the synthesis of other organic compounds and as a reducing agent in certain reactions.