Breathing simply explained:

Respiration (lat. Respirare = respiration) or respiration is an ambiguous term used in biology, which requires a more precise definition. Outside breathing describes the absorption of oxygen from the air. These include, for example, pulmonary respiration (mammals), gill respiration (fish) or tracheal breathing (insects). In everyday language, breathing is usually associated with just this active process of oxygen uptake and carbon dioxide release.
Everything that happens afterwards at the cellular level in the body concerns the inner breathing, This serves for the actual energy production (ATP) of the cell.
Depending on whether oxygen is needed for the inner respiration, one differentiates between aerobic and anaerobic respiration:
Aerobic respiration: The energy obtained in aerobic respiration occurs only in the presence of elemental oxygen (the oxygen is not in a bond with other elements). In this context, one also speaks of cellular respiration. These include processes such as glycolysis, the citrate cycle and the respiratory chain. If the oxygen is missing, the aerobics will die off after a short time.
Anaerobic respiration: In anaerobic respiration, the energy is obtained even without the presence of oxygen. Most anaerobes are found in the unicellular prokaryotes.
Special cases are fermentation processes such as lactic fermentation or alcoholic fermentation. Although these processes take place without oxygen consumption, strictly speaking, they do not belong to anaerobic respiration.