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Definition of classification

• The placing of topics into categories
• System for organizing, categorizing knowledge

Purpose of classification

• Bring related items together in a useful sequence from the general to the specific
• Enable customers to browse collections on a topic, either in person or online

Scope of NLM Classification

• Covers the field of medicine and related sciences
• Broad classification adaptable for special collections of any size or format

Historical Development

• Print edition (1951-1999); updated infrequently
• Online edition (2002-2016); updated annually; (2017- ) twice-yearly updates
• PDF (2006- ); updated annually
• Poster (2005- ); updated irregularly as needed