Stearic acid is a saturated fatty acid with the chemical formula C18H36O2. It is a white, waxy solid that occurs naturally in various animal and vegetable fats. Stearic acid is widely used in the manufacturing of cosmetics, pharmaceuticals, candles, plastics, and soaps. In cosmetics and personal care products, it serves as an emulsifying agent and thickener, helping to stabilize and improve the texture of creams, lotions, and other products. Stearic acid can also be found in many food products, where it functions as a food additive (E number E570) and an emulsifying agent.

In candle making, stearic acid is added to wax formulations to increase the hardness and opacity of candles, as well as to reduce dripping. Additionally, it is used in the production of industrial lubricants, metal soaps, and various other chemical compounds. Stearic acid is generally regarded as safe for use in consumer products when used as directed.