Glycerin is present in all natural lipids (fats), whether animal or vegetable.
It can be manufactured by the hydrolysis of fats and by the fermentation of sugars.
Glycerin is a humectant that aids the skins natural protection by filling in the area known as the intercellular matrix and by attracting just the right amount of water to maintain the skins homeostasis. In other words, it draws moisture to the skin. There is also research indicating that the presence of glycerin in the intercellular layer helps other skin lipids do their jobs better (Sources: American Journal of Contact Dermatitis, September 2000, pages 165–169; and Acta Dermato-Venereologica, November 1999, pages 418–421). It is supplied as a clear, viscous liquid that is water-soluble.