Reflection of dynamic theory of classification in universal decimal classification

Classification is the process of division and grouping of entities because of dissimilarities and similarities, their logical arrangement in the group and representation of each group by its unique pre-dominant characteristics. Or it is the action of classifying or categorizing or sorting of something. For example, division of living organisms into two groups viz. plant kingdom and animal kingdom because of their distinguished characteristics. It is a methodically grouping of things according to their salient features. The classified entity is a concept (an idea) or a complex of concepts, which is an acquired subjective representation of a real but not necessarily observable unit. The groups are arranged logically according to certain decided principle or standard, so that the relationships among them or inference of one group from another are clearly indicated.

It is rightly said that necessity is the mother of invention. This is true in case of genesis of Universal Decimal Classification (UDC) also. When UDC was conceived, there were only DDC and Expansive classification systems in use. Dewey Decimal Classification (DDC) which had its origin in 1876 had reached its 5th ed. DDC was developed for shelf arrangement of books on the shelves. As literature was growing and becoming out of bibliographical control, two Belgians, Paul Otlet and Henri La Fontaine thought of compiling an index/bibliography at international level.