Sulfates are inorganic salts of sulfuric acid, widespread in foods, water, and the environment. They include familiar compounds such as calcium sulfate, used as a coagulant in tofu and a dough conditioner, and magnesium sulfate (Epsom salt). In water they contribute to hardness and, at high levels, a laxative effect and bitter taste, so drinking-water standards limit them. In food processing they serve as firming agents, nutrient sources for fermentation, and mineral supplements. Their chemistry is generally benign, but levels matter for both quality and health.