In any science, the problem of classification and typologization belongs to one of the leading problems, since it allows ordering and systematizing the objects and phenomena that make up the object and the subject of its investigation. In library science, the issues of classification and typology of libraries were actively discussed during the entire 20th century, there are much less positive changes in this direction than one might expect, given the importance of the topic and the credibility of the developers.

The earliest attempts to classify libraries are related to the realization of one of the pragmatic management functions of accounting. With the emergence of the need to divide the total set of libraries into specific groups, the libraries attempted to group the libraries according to different criteria to process the information they received, primarily by their belonging to the founders and the location. Realizing the importance of information about the activities of libraries to determine the degree of education and mental needs the first attempt was made in 1864, presenting the experience of gathering and giving the most important information about libraries extracted from various printed sources. Particularly active issues of organizing the collection and grouping of information about libraries were discussed at the congress on Library Science in countries of the world. The question of the statistical grouping, and accordingly of the classification of libraries, turned out to be ineffective. The main feature of the classification of libraries remained geographical.

At the heart of the construction of any classification are the properties of the objects under consideration. Based on the provisions of the system approach, they can be divided into two groups, determined by the external and internal environment. Each of the elements of the library’s external environment serves as a basis for singling out one or more classification features. Among the most important elements of the external environment that generate classification signs, it is necessary to name the society as a whole and the state that determines the forms of ownership, the mechanism for establishing and financing its institutions, administrative-territorial division and other attributes of the activities of libraries.

This book aims to help readers understand classification system in library collections with examples of different countries around the world. The book covers following major points for readers to understand the classification of system: Dewey’s Decimal Classification, Universal Decimal Classification (UDC), Characteristics of the Library System, and typology of libraries, classification of libraries and principles of library activity.