The reactions in which oxidation and reduction are taking place at the same time are called redox reactions.
For examples:
In the above example, Fe2O3 is reduced to Fe by losing oxygen atoms.
Thus, Fe undergoes reduction.
CO is oxidized to CO2 by gaining oxygen atom. Thus, C undergoes oxidation.
CuO + H2→ Cu + H2O
In the given reaction, CuO is reduced to Cu by losing oxygen. Thus, Cu undergoes reduction.
H2 is oxidized to H2O by gaining oxygen atom. Thus, H2 undergoes oxidation.
