Orthophosphoric acid (PA) is a colorless, viscous liquid or crystalline solid under standard temperature and pressure (pure substance melts at 42°C). Commercially available products are typically colorless, transparent aqueous solutions with a concentration of approximately 85% and a mild sour taste. It is a moderately strong ternary inorganic acid with active chemical properties: it can ionize hydrogen ions in three steps, exhibiting the general characteristics of acids; it reacts with bases to form phosphates, hydrogen phosphates, and dihydrogen phosphates; it readily dehydrates and condenses upon heating to generate pyrophosphoric acid, polyphosphoric acids, etc.; and it can act as a ligand to form complexes with metal ions. Based on these properties, its primary applications include: serving as a key raw material for phosphate fertilizers (e.g., ammonium phosphate) and compound fertilizer production; used in manufacturing detergents, water treatment agents, and metal surface treatment agents; acting as an acidity regulator and preservative in the food industry; and employed in the preparation of flame retardants, refractory materials, pharmaceutical intermediates, and lithium-ion battery electrode materials, among others.