Fermentation is the process by which glucose is converted into either alcohol or lactic acid in the absence of oxygen. It is also known as anaerobic respiration. Fermentation occurs in some bacteria, yeasts and in the muscles during heavy exercise.
Glycolysis
Glycolysis is the process which occurs in cytoplasm of all living organisms. In glycolysis one molecule of sugar is broken down into two molecule of pyruvate producing net two molecules of ATP, two molecules of NADPH and two molecules of water. In anaerobic organisms glycolysis is known as fermentation.