The Dewey Decimal Classification (DDC) is structured around ten main classes covering the entire world of knowledge; each main class is further structured into ten hierarchical divisions, each having ten divisions of increasing specificity. As a system of library classification, the DDC is "arranged by discipline, not subject", so a topic like clothing is classed based on its disciplinary treatment within the conceptual framework. The following list presents the ten main classes, hundred divisions, and thousand sections.