Cellular respiration primarily occurs in the mitochondria of cells. Mitochondria are often referred to as the "powerhouses of the cell" due to their central role in energy production. It is within the mitochondria that the various stages of cellular respiration, including glycolysis, the Krebs cycle (also known as the citric acid cycle), and oxidative phosphorylation, take place. These processes involve the breakdown of glucose and other organic molecules to generate energy in the form of ATP (adenosine triphosphate).