Fundamentally, redox reactions are a family of reactions that are concerned with the transfer of electrons between species.
Oxidation refers to the loss of electrons , while reduction refers to the gain of electrons.
If a chemical causes another substance to be oxidized, we call it the oxidizing agent. Oxidants get reduced in the process by a reducing agent. The oxidation number is defined as the effective charge on an atom in a compou nd, calculated according to a prescribed set of rules. An increase in oxidation number corresponds to oxidation, and a decrease to reduction. The rules are shown below.