How is Glycolysis essential for the production of ATP.

Glycolysis is a process that takes glucose, combines it chemically with oxygen, and produces free energy in the form of ATP (adenosine triphosphate).  It is one of the chief processes responsible for energy production in cells.  In animal cells, food is digested by the digestive system, progressively broken down into smaller units, until the glucose contained in the food is absorbed by the small intestine.  The glucose enters the bloodstream, where it is taken to all the cells in the body.  Oxygen is absorbed in the alveoli of the lungs, where it enters the bloodstream of the body to be taken to all cells.  Glycolysis represents the first of about ten steps of energy production within the mitochondria of cells.  It breaks apart the glucose molecule into basic components, which are then chemically combined to make other products (waste) and free energy for the cell to conduct its life processes, in the form of ATP.