Generic name of bivalent aliphatic alcohols. The various glycols are named after the hydrocarbon radical to which the alcoholic hydroxyls (g. ethylene, g. propylene, etc.) are bind, or from the hydrocarbon of origin by adding the suffix -diol (ethanediol, propanediol, etc.).

In general, glycols or polyalcohols are organic substances that have more than one alcohol group OH.

The most important is glycerol, commonly called glycerin, which is present in main fats, such as triglycerides and phospholipids.

The alcohol group plays a primary role in the composition of the main biological molecules, being present in sugars, nucleic acids, some amino acids, etc.

The simplest glycols are usually viscous and colourless, while the complex glycols, often called superior glycols (which are marked by a high solubility in water), are usually crystalline (solid). When hydroxyls are placed on several carbon atoms, they are stable showing a marked solubility in water and a low solubility in non polar solvents.