categorization, categorisation, classification, compartmentalization, compartmentalisation, assortment

the act of distributing things into classes or categories of the same type

• indexing — the act of classifying and providing an index in order to make items easier to retrieve
• reclassification — classifying something again (usually in a new category)
• relegation — the act of assigning (someone or something) to a particular class or category
• stratification — the act or process or arranging persons into classes or social strata
• taxonomy — practice of classifying plants and animals according to their presumed natural relationships
• typology — classification according to general type

• grouping — the activity of putting things together in groups