What is UDC?
The UDC is the world's foremost multilingual classification scheme for all fields of knowledge and a sophisticated indexing and retrieval tool. It is a highly flexible classification system for all kinds of information in any medium. UDC provides a systematic arrangement of all branches of human knowledge organized as a coherent system in which knowledge fields are related and inter-linked.

Originally based on the Dewey Decimal Classification, the UDC was developed as a new analytico-synthetic classification system with a significantly larger vocabulary and syntax that enables very detailed content indexing and information retrieval in large collections.

Because of its logical hierarchical arrangement and analytico-synthetic nature, it is suitable for physical organization of collections as well as document browsing and searching. The UDC is structured in such a way that new developments and new fields of knowledge can be readily incorporated. The code itself is independent of any particular language or script (consisting of arabic numerals and common punctuation marks), and the accompanying class descriptions have appeared in many translated versions.
Who is using UDC?
The scheme is in worldwide use, and has been published in whole or in part in over 40 different languages (see bibliography of UDC editions). UDC is used in around 150,000 libraries in 130 countries and in many bibliographical services which require detailed content indexing. In a number of countries it is the main classification system for information exchange and is used in all type of libraries: public, school, academic and special libraries.

Read More: http://blog.goodbooksafrica.com/2014/08/universal-decimal-classification-udc.html