Almost anything — animate objects, inanimate objects, places, concepts, events, properties, and relationships — may be classified according to some taxonomic scheme. Wikipedia categories illustrate a taxonomy schema.
The term taxonomy may also apply to relationship schemes other than parent-child hierarchies, such as network structures with other types of relationships. Taxonomies may include single children with multi-parents, for example, "Car" might appear with both parents "Vehicle" and "Steel Mechanisms"; to some however, this merely means that 'car' is a part of several different taxonomies.
A taxonomy might also be a simple organization of kinds of things into groups, or even an alphabetical list. However, the term vocabulary is more appropriate for such a list. In current usage within "Knowledge Management", taxonomies are seen as less broad than ontologies as ontologies apply a larger variety of relation types.
Mathematically, a hierarchical taxonomy is a tree structure of classifications for a given set of objects. It is also named Containment hierarchy. At the top of this structure is a single classification, the root node, that applies to all objects. Nodes below this root are more specific classifications that apply to subsets of the total set of classified objects. So for instance, in common schemes of scientific classification of organisms, the root is called "Organism" followed by nodes for the taxonomic ranks: Domain, kingdom, phylum, class, etc. The progress of reasoning proceeds from the general to the more specific.
In contrast, in a context of legal terminology, an open-ended contextual taxonomy -- a taxonomy holding only with respect to a specific context. In scenarios taken from the legal domain, a formal account of the open-texture of legal terms is modeled, which suggests varying notions of the "core" and "penumbra" of the meanings of a concept. The progress of reasoning proceeds form the specific to the more general.
In phylogenetic taxonomy, cladistic taxonomy or cladism, organisms are classified into "clades", which are discovered by grouping taxa using derived traits. By using clades as the criteria for separation, cladistic taxonomy, using cladograms, can categorize taxa into unranked groups. The taxonomy is exclusively based on cladistic analysis.
In numerical taxonomy, phenetics or taximetrics, the taxonomy is exclusively based on cluster analysis and neighbor joining to best-fit numerical equations that characterize all measurable quantities of a number of organisms. This method has been largely superseded by the superior cladistic analyses today, except in cases when these are too computationally intensive (a single large-scale cladistic analysis can take months to compute).
The neologism folksonomy should not be confused with "folk taxonomy", though it is obviously a contraction of the two words. "Fauxonomy" (from French faux, "false") is a pejorative neologism used to criticize folk taxonomies for their lack of agreement with scientific findings. Baraminology is a taxonomy used in creation science which in classifying form taxa resembles folk taxonomies.
The phrase "enterprise taxonomy" is used in business to describe a very limited form of taxonomy used only within one organization. An example would be a certain method of classifying trees as "Type A", "Type B" and "Type C" used only by a certain lumber company for categorising log shipments.
The term "military taxonomy" encompasses the domains of weapons, equipment, organizations, strategies, and tactics. The use of taxonomies in the military extends beyond its value as an indexing tool or record-keeping template. In the 21st century, the ambit of a subset taxonomy of terrorism would include terms related to terrorists, terrorist groups, terrorist attacks, weapons, venues, and characteristics of terrorists and terrorist groups.
A taxonomy of terms to describe various types of military operations is fundamentally affected by the way in all elements are defined and addressed -- not unlike framing. For example, in terms of a specific military operation, a taxonomic approach based on differentiation and categorization of the entities participating would produce results which were quite different from an approach based on functional objective of an operation (such as peacekeeping, disaster relief, or counter-terrorism). An incidental advantage which flows from give-and-take in refining taxonomic terms more accurately and efficiently becomes more than a worthwhile objective in terms of anticipated outcomes or results. In today's nontraditional operations, the discussion about fundamentals also generates greater precision in how the defense and security community understands and discusses integrated operations.
A number of military strategies can be parsed using a taxonomy model. The comparative theoretical framework might posit a range of criteria, e.g., the character of envisaged political goals, the type of military strategy preferred, and the scope of forces engaged; and this template suggests discrete modes of force. The taxonomy-model analysis suggests a useful depiction of the spectrum of the use of military force in a political context.