What part of a reaction involves oxidation or reduction, but not both?
Half equations, which we use to solve redox reactions.
Consider the reduction of intensely purple
As written, this is a reduction reaction, the which includes electrons, which are conceived to reduce the manganese centre. The reduction reaction must be accompanied by a corresponding oxidation reaction to supply the electrons.
I acknowledge that the use of electrons is a little bit abstract; but their use indicates electron transfer, which characterizes redox behaviour and allows us to balance such equations.