Triglycerides are formed from the esterification of 3 molecules of fatty acids with one molecule of trihydric alcohol, glycerol (glycerine or trihydroxy propane). In the process, 3 molecules of water are eliminated. The word "triglyceride" refers to the number of fatty acids esterified to one molecule of glycerol.
In triglycerides, the three fatty acids are rarely similar and are thus called pure fats. For example, tripalmitin, tristearin, etc.