Oxidation-reduction, often called redox, is a chemical process involving the transfer of electrons between substances. In this process, one substance loses electrons and undergoes oxidation, while another gains electrons and undergoes reduction. This electron transfer is essential in many chemical reactions, including those in batteries and biological systems. In a redox reaction, the substance that donates electrons is known as the reducing agent, and the one that accepts electrons is the oxidizing agent. These reactions are crucial for energy production in living organisms, as well as in industrial applications like metal extraction and corrosion processes.