Structure of Glycerol:

IUPAC name: Propane-1,2,3-triol

Here, the –OH groups are the functional groups. The number of carbon atoms in the above structure is 3 and all the bonds between the Carbon atoms are single bonds. So, the IUPAC name starts with Propane. Three –OH groups are attached to the Carbon atoms at position 1, 2 and 3. Therefore, the IUPAC name of glycerol is Propane-1,2,3-triol.