The formation of water occurs when two hydrogen atoms bond with one oxygen atom. This process can happen through a chemical reaction, where hydrogen gas (H2) reacts with oxygen gas (O2) to produce water (H2O). The reaction releases energy in the form of heat, making it an exothermic process. In nature, water is often formed during combustion reactions, such as when fossil fuels are burned. Additionally, water can be produced through various biological processes, including cellular respiration, where organisms convert glucose and oxygen into energy, releasing water and carbon dioxide as byproducts.