Chemical reactions involving oxidation and reduction processes are called redox reactions. Oxidation may be defined as the process in which a species (atom, molecule or ion) increases oxidation number by losing one or more of electrons. The substance undergoing oxidations is called reducing agent reaction, on the other hand, is a process in which a species (atoms, molecules or ions) decreases oxidation number by gaining one or more electrons. The species undergoing reduction is called oxidizing agent. Neither oxidization nor reduction can take place alone. Redox reaction can, thus, be termed as the chemical reaction involving transference of electrons from reducing agent to oxidizing agent.