oxidation-reduction

Oxidation-reduction (redox) describes a chemical process where electrons are transferred between substances. Oxidation is when a substance loses electrons, often resulting in a positive change in its charge. Reduction is when a substance gains electrons, leading to a negative change in charge. These processes always occur together; one substance's loss of electrons (oxidation) enables another to gain them (reduction). Redox reactions are fundamental to many natural and industrial processes, such as how batteries generate electricity, how our bodies metabolize food, and how metals corrode.