With each member of the first set we associate, in a natural way a member of the second set. It is in the process of associating members of one set with the members of another set that something new has been created. Let us analyse the situation mathematically. Denote the set of persons by “P” and the set of names by “N”. We want to associate with each member of “P” an appropriately chosen member of N; in fact, we want to create a mathematical objects which will characterize this association of members of N with members P. We rely on one simple observation: there is no better way of indicating that two objects, one after the other; i.e., we indicate that two objects are associated by pairing the objects. Now we see the importance of ordered pair (a, b) can be used to indicate that a and b are linked together.