Redox chemistry, or reduction-oxidation chemistry, is a fundamental concept describing chemical reactions that involve the transfer of electrons between chemical species. Oxidation is defined as the loss of electrons from a species, which typically results in an increase in the oxidation state. Conversely, reduction is the gain of electrons, leading to a decrease in the oxidation state. Since both processes occur simultaneously in a coupled reaction, the overall process is classified as redox. This principle is central to many natural and technological systems, governing energy storage and release in biochemical pathways, as well as the functionality of electrochemical cells. The ability to quantify electron transfer drives understanding in fields from material science to metabolism.