Taxonomy Design
Definition
The practice of creating hierarchical classification systems that organize concepts into parent-child relationships. Taxonomies provide structure for navigation, search, and sense-making.
Design Principles
Mutual Exclusivity: Items belong in one place (or use polyhierarchy intentionally) Exhaustive Coverage: Everything has a home Balanced Depth: Consistent granularity across branches User-Centered: Categories match user mental models, not internal structures
Process
- Gather: Collect items to be classified
- Group: Card sort into natural clusters
- Label: Name groups in user language
- Arrange: Create hierarchy (top-down and bottom-up)
- Validate: Test with real users and content
- Iterate: Refine based on use
Taxonomy vs. Ontology
Taxonomies are simpler: just hierarchical is-a relationships. Ontologies add multiple relationship types, attributes, and inference rules. Start with taxonomy; add ontology complexity only when needed.
Maintenance Challenge
Taxonomies drift as domains evolve. Without governance, they become inconsistent, outdated, and unusable. Plan for evolution from the start.
Common Failures
- Designer categories vs. user categories
- Too deep (lost in hierarchy) or too shallow (no structure)
- Ambiguous labels (what goes where?)
- No process for new items
Related: 02-molecule—faceted-classification, 02-molecule—five-hat-racks