The oxidation and reduction reactions in aqueous solutions involve the transfer of electrons from one species to another. In the oxidation of a substance electron(s) is (are) transferred from the species and in reduction, electron(s) is (are) gained by the species. Oxidation and reduction reactions occur simultaneously. A reaction, which involves simultaneous oxidation and reduction, is called a redox reaction. The titrations involving redox reaction are called redox titrations. In Redox titrations involving potassium permanganate, it acts as a powerful oxidising agent.
This video explains how to determine the strength of potassium permanganate solution by titrating it against a standard solution of Oxalic acid.