A reaction that occurs when a substance loses electrons is termed an oxidation reaction. In this process, the oxidizing agent gains electrons while the substance undergoing oxidation is transformed. Oxidation is a key component of many chemical reactions, particularly in redox reactions, where reduction and oxidation occur simultaneously. This process is fundamental in areas including metabolism, combustion, and the functioning of batteries. Understanding oxidation is critical for fields such as biochemistry, environmental science, and energy technology.