Let's look at an example. Oxidation of Alcohols In organic chemistry, a useful definition of oxidation is a reaction in which the product has more oxygen atoms than the reactant, or one in which the product has fewer hydrogen atoms than the reactant, or both. Alcohols provide examples. Many oxidation reactions of alcohols are important steps in biological processes. We'll see examples later.
Reduction is the opposite of oxidation.
We have seen an example in hydrogenation of alkenes, and we will see more examples.