Introduction

The Universal Decimal Classification (UDC) is a general classification scheme for all branches of human knowledge. It was created by two Belgian lawyers—Paul Otlet and Henry LaFontaine—in 1895.

Otlet and LaFontaine first developed the UDC in order to provide a systematic arrangement for their bibliography—Repertoire bibliographique universel—which was meant to be a bibliography of everything that had been published. They based their UDC on the fifth edition of the Dewey Decimal Classification (DDC) schedules (they negotiated an agreement with Melvin Dewey for its use).

Otlet and LaFontaine expanded the main and auxiliary tables and added certain synthetic devices-in order to handle a great deal of their bibliographic list and to introduce some flexibility into the rigid structure of the DDC. Eventually, the task of compiling a bibliography was abandoned but the remaining arrangement structure survived and became what is now known as the UDC.