The Dewey Decimal Classification (DDC) system, devised by library pioneer Melvil Dewey in the 1870s and owned by OCLC since 1988, provides a dynamic structure for the organization of library collections. Now in its 23rd edition, the DDC is the world's most widely used library classification system. The 23rd edition includes several major changes held for simultaneous publication in the print and Web versions of the DDC plus many interim updates. - Publisher.