At a higher level, fermentation in plants and animals allows the creation of ATP from the pyruvates produced from glycolysis. For more details, you can check the following link:answers.yahoo.com
What Is The Advantages Of Fermentation?
Do you mean fermentation in the metabolism, the use of fermentation in food preparation or the fermenting process in wine production? Perhaps you mean the advantages of different forms of fermentation - in any case, you can find a detailed explanation of the different processes here.