The main purpose of cellular respiration is to convert biochemical energy from nutrients into ATP, the energy currency of the cell. This process occurs in three main stages: glycolysis, the Krebs cycle, and the electron transport chain. During these stages, energy stored in various molecules, particularly glucose, is gradually released and captured in the form of ATP. Cellular respiration is crucial for maintaining cellular activities, as ATP provides the necessary energy for processes such as muscle contraction, nerve impulse transmission, and biosynthesis of macromolecules.