What is metal coupling?

Hint: In chemistry, periodic tables play a vital role. In the periodic table there are totally \[118\] elements. In the periodic table there are totally \[18\] columns and \[7\] rows. The columns are called groups. Hence, \[18\] groups in the periodic table. The rows are called periods. Hence, totally \[7\] period in the table. Iron is one of the metallic elements in the periodic table. The symbol of iron is derived from Latin form ferrum. It is present in the first transition series. Iron is the fourth most common element in the earth crust in the elemental list. The appearance of the iron is lustrous metallic with greyish color. Each element in the periodic table has a certain group and period. In that case iron is one of the elements in the period. The atomic number of iron is \[26\] and the symbol is \[{\text{Fe}}\]. The mass number of the iron is \[55.845\].

Complete answer:
We have to know that the metal reacts with the environment or chemicals due to this reaction the gradual destruction of metal is known as corrosion. It is one of the oxidation reactions in chemistry.
Metal coupling is nothing but one of the methods for preventing the rusting of iron. The electro-positive metals like magnesium, zinc or aluminium are used for coupling to prevent the rusting of iron is known as the metal coupling.
According to the above discussion, we conclude metal coupling is the method for preventing the rusting of iron.

Note:
We need to know that in chemistry two main reactions play a major role. One is the oxidation reaction. Another is the reduction reaction. Oxidation reaction is nothing but addition of oxidation or removal of hydrogen or loss of electrons. Reduction is nothing but addition of hydrogen or removal of oxygen or gain of electrons in the reaction form reactant to product. For oxidation and reduction purposes using some reagents, reagents are called oxidising and reducing agents. The oxidising agent is nothing but the reagent is used for oxidation of reactant to give respect to the product.