Glycerol (HOCH2CH(OH)CH2OH or C3H8O3), or glycerin, is a clear, colourless, viscous, sweet-tasting liquid organic compound of the alcohol family. With three hydroxyl groups, it can form three types of esters (monoglycerides, diglycerides, and triglycerides). Mono- and diglycerides are common food additives. Fats and oils are triglycerides; their processing into soap was the chief source of glycerol until the mid-20th century, when industrial synthesis took over.
Glycerol has thousands of uses, including as an emulsion, softening agent, plasticizer, and stabilizer in baked goods, ice cream, and tobacco; in skin lotions, mouthwashes, and cough medicines; as a protective medium for freezing red blood cells, sperm, corneas, and other tissues; in printing inks and in the gums and resins in paints and coatings; in antifreeze mixtures; as a nutrient in fermentation; and as a raw material for nitroglycerin.