Taxonomy is the science and practice of classification. It involves two distinct parts: developing a scheme of classes and allocating specific items to those classes. For marketers and SEO practitioners, a well-structured taxonomy helps users find information quickly and improves the relevance of search engines within specific domains.
Entity Tracking
- Taxonomy: The practice and science of classification or categorization of concepts, things, or organisms.
- Classification: The process of allocating specific items or entities into predefined classes or categories.
- Taxon: A specific unit or node within a taxonomic scheme, such as a category in a hierarchy.
- Is-a relationship: A hierarchical connection where a specific object is treated as an instance of a broader concept.
- Has-a relationship: A connection describing a part-whole link where one entity is a component of another rather than a subtype.
- Hyponymy: A linguistic relationship where a specific term (hyponym) falls under a broader category name (hypernym).
- Folksonomy: An informal classification system generated by user-applied tags rather than a top-down hierarchy.
- Ontology: A complex relationship scheme that uses a wider variety of relation types than a traditional hierarchical taxonomy.
- Mereology: The formal study of part-to-whole relationships as opposed to subtype relationships.
- Typology: A classification system based on abstract or subjective criteria rather than empirical, objective characteristics.
What is Taxonomy?
Taxonomy organizes taxonomic units known as "taxa" into structures, most commonly parent-child hierarchies. While the term was [originally coined in 1813 to describe the classification of organisms] (Wikipedia), it now applies to any system that organizes documents, videos, or digital concepts.
In a mathematical sense, a hierarchical taxonomy is a tree structure. It begins with a single root node that applies to all objects, while lower nodes represent more specific subsets.
Why Taxonomy matters
Taxonomy serves as the backbone for information retrieval and user experience. * Findability: Helps users locate specific items within a website or database more easily. * Search Relevance: Acts as a tool to improve the relevance of search results within a vertical domain. * User Mental Models: A well-designed hierarchy allows users to develop a mental model of a site structure, making it feel intuitive. * Cross-referencing: Standardized systems, such as the [Linnaean system created in the 1750s] (Britannica), simplify information discovery across different platforms.
How Taxonomy works
Taxonomy works through relationships and structural logic.
Hierarchical structures Most taxonomies use "is-a" models. For example, a "car" is-a "vehicle." This is distinct from "has-a" relationships, like an "elephant" has-a "trunk." In linguistics, these are called hyponyms (specific) and hypernyms (broad).
Methodological approaches * Logical Division: A top-down approach that divides a broad class into subclasses based on "essential" characteristics. * Phenetics (Numerical Taxonomy): A bottom-up approach that clusters items based on observable, measurable similarities. * Pragmatic Classification: Organizing items based on goals or consequences, such as grouping kitchenware by how it is used rather than what it is made of.
Web Taxonomy best practices
Writing for the web requires balancing user needs with technical structure.
- Maintain category exclusivity: Aim for mutually exclusive categories. While "cross-listing" (placing one item in multiple categories) is possible, the hierarchy lose its value if used too often.
- Balance breadth and depth: If you provide too many options at one level, you overload the user.
- Limit click-through levels: Users may become frustrated if they must click through too many layers. [Information architecture experts suggest keeping structures to two or three levels] (Wikipedia).
- Align with population norms: Large populations tend to [develop highly similar category systems naturally] (Wikipedia), so use terms that reflect common user language.
Common mistakes
Mistake: Creating a "polyhierarchy" where categories overlap constantly. Fix: Refine category definitions to ensure they are as mutually exclusive as possible.
Mistake: Designing an "alphabetical list" and calling it a taxonomy. Fix: Use an alphabetical list for a vocabulary, but use a taxonomy to show how items relate to one another.
Mistake: Ignoring change in concepts. Fix: Update taxonomies when scientific or industry standards shift. In astronomy, for example, the [reclassification of the Sun and Moon changed the concepts of "star" and "planet"] (Wikipedia).
Examples
- Corporate Taxonomy: A hierarchical classification of entities of interest to an enterprise, such as departments or asset types.
- Industry Codes: Systems like the North American Industry Classification System (NAICS) or the Standard Industrial Classification (SIC).
- Knowledge Management: Using a manually constructed taxonomy like [WordNet to restructure Wikipedia categories] (Wikipedia), a method proven effective in 2009.
- Sustainable Activities: The [EU taxonomy established to clarify which investments are environmentally sustainable] (Wikipedia).
Taxonomy vs. Typology
| Feature | Taxonomy | Typology |
|---|---|---|
| Criteria | Empirical and objective | Abstract or subjective |
| Logic | Based on observable traits | Based on conceptual types |
| Goal | General classification | Grouping by ideal forms |
FAQ
What is the difference between taxonomy and classification? Taxonomy is the science and the scheme itself. Classification is the actual act of placing an item into that scheme.
How many levels should a website taxonomy have? General guidelines suggest a balance where users do not have to click through more than two or three levels, as excessive depth causes frustration.
Is a folksonomy the same as a taxonomy? No. A taxonomy is usually a controlled, top-down hierarchy. A folksonomy is a bottom-up system based on user-generated tags.
What is an "is-a" relationship? It refers to a specific instance belonging to a broader category. For example, "Fido" is-an instance of the concept "dog," and "dog" is-a "mammal."
How does DNA analysis affect taxonomy? In biological taxonomy, modern DNA analysis often reveals that species previously thought to be related are different. This causes "taxonomic flux," where classifications must be rewritten to reflect new data.
