From the above definitions, and descriptions, the essential characteristics of classification may be outlined as under:
There should be clarity in the terms on the basis of which the classification of data is made. For instance, when data relating to population are classified into two classes, say literates and illiterates should be defined in clear manner without leaving any room for ambiguity. Unless the terms of classification are defined clearly, the whole purpose of classification will be vitiated on the point of confusion and ambiguity.
The meaning of the different terms viz., literate, religion, occupation, etc. used in the classification should remain stable for a reasonable period. Make a comparative analysis of data thus classified. For instance, the occupational classification in the Indian census in which various occupations have been defined in different ways in the successive censuses suffers from this defect.
Along with stability, the process of classification should remain flexible to adjust with the changes in course of time. With the passage of time, some classes of data may become obsoletc and some new classes of data may appear relevant. In such cases, the obsolete classes need to be removed, and the new relevant classes need to be added. This requires adjustability, or flexibility of the process of classification to allow for such deletion and addition of the obsolete and uptodate classes respectively. For this, the data should be classified into a few major groups which should remain capable of further subdivisions according to the demand of time. This way, the classification can retain both the contradicting characters of stability and flexibility.