A review of glycerin/glycerol was recently published in the World’s Poultry Science journal. The authors reported that glycerin or glycerol (C3H5(OH)3) is one of the most valuable and versatile chemical materials known. The term ‘glycerin’ refers in general to a commercial solution of glycerol in water of which the main constituent is glycerol. Glycerin is an odorless, colorless, viscous liquid with a sweet taste. It is completely soluble in both alcohol and water. Glycerin is the main co-product derived from biodiesel production. It is produced by a KOH- or NaOH-catalysed transesterification of the triacylglycerols in fat or oil along with an alcohol. Glycerin is an important ingredient for the production of soaps, cosmetics, pharmaceuticals and food. Additionally, glycerin is highly stable under normal storage conditions, practically non-irritating in its different uses, suitable for interactions with other chemical materials and has no negative environmental impacts. Nowadays, with increasing glycerin production and its availability on the market, many new and novel uses are expected to be developed, particularly as alternative energy source for poultry diets. Furthermore, glycerin plays an essential role in body cellular metabolism. The reviewers discussed various trials using glycerin in poultry diets as an energy source and its effects on different parameters in the birds. In general positive responses were reported in most studies when glycerin was included in poultry diets up to ten percent.