Hint:There are usually two types of reactions that are oxidation and reduction. In oxidation we observe that the electrons are being lost by the atom in the chemical reaction whereas in reduction the atom is gaining electrons. When both the reactions occur simultaneously in the same reaction then it is known as a redox reaction where both oxidation and reduction takes place.
Complete step-by-step answer:Reduction is defined as the chemical process which can be explained in many ways. So if we explain it in terms of oxygen then during reduction the substance loses oxygen in a chemical reaction. When the substance loses oxygen it gets reduced and the process of reduction takes place. But if we explain reduction in terms of electron transfer then in reduction the substance gains electrons to get reduced. In terms of transfer of hydrogen, the substance gains hydrogen to get reduced. During the reduction we observe that the substance oxidation state gets decreased. While in oxidation we observe that the loss of electrons takes place. In oxidation the substance oxidation state get increased. The gain of oxygen and loss of hydrogen is seen in the oxidation. The example of oxidation and reduction in one reaction only is the following: \[CuO+Mg\to Cu+MgO\] Here the copper oxide gets reduced to copper by losing oxygen that means it is the reduction reaction. Whereas the magnesium gets oxidised to magnesium oxide by gaining oxygen so it is the oxidation reaction. And here both oxidation and reduction reactions are taking place so it is a redox reaction.
Note:The oxidation is a process in which the substance oxidised itself whereas the oxidising agents are the substance which itself gets reduced and tends to oxidise the other atoms. Whereas the reducing agents are those which oxidise themselves and reduce the other substances. Whereas in reduction the substance reduces itself.