Cellular Respiration is a metabolic process that releases energy from food through oxidation to produce ATP, which provides energy for cells' activities. It involves three main stages: 1) Glycolysis produces some ATP. 2) The Krebs cycle further breaks down molecules and produces more ATP and electron carriers. 3) The electron transport chain uses the electron carriers to produce the most ATP through an energy-releasing process that uses oxygen. Overall, cellular respiration yields 36 ATP through these three stages of breaking down glucose with oxygen.