Information Architecture Institute Glossary

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Glossary Term:

Definition:

    Taxonomy was originally coined to describe the hierarchical classification scheme of living things (the Linnaean taxonomy).

    More recently it has been used to describe any information organization or classification scheme, including simple lists and networks, since the basic meaning of the word is a method of arrangement.

    But the most common kind of taxonomy is still a hierarchy (or tree) with a top element (or root), depending on your preference for Top Down or Bottom Up design. Nodes (or branch points) are names for things (objects) or concepts. In a simple taxonomy, each item being classified fits in just one place in the taxonomy, with a single parent and any number of children.

    Biological classification schemes attempt to arrange organisms in a seven-level taxonomy - kingdom, phylum (or division for plants), class, order, family, genus, and species. This natural taxonomy arranges all living things. Things in a subclass are the same type of thing (living organisms) as the members of its parent class.

    A library classification scheme (like DeweyDecimal? or LibraryOfCongress?) puts each book in a single spot (literally on a certain shelf) in the library.

    A Controlled Vocabulary may be arranged in a taxonomy, where the things arranged are simply words, names, or concepts. When a Controlled Vocabulary has definitions, it becomes a Glossary?. Glossaries are rarely arranged in a hierarchy, preferring a simple alphabetical order. like this one.

    The items in a subclass (e.g., species) may not be the same type of thing as in the parent class (e.g., genus). The hierarchy may consist of container classes (wholes) with subclasses containing parts. Such a taxonomy is sometimes called a partonomy or mereology.

    A computer file system has a root folder or directory with named files and folders or directories, each of which contains a number of files and folders or directories, to an arbitrary depth. Note that files and folders are not the same type of thing, and files may be of different types (documents, multimedia, etc.).

    Similarly, a website has a home page (root) and an implicit DrillDownPath? (see Bread Crumbs) to the subsites and the contained pages. Some websites have an underlying file system that mirrors (is isomorphic with) the website organization.

    The DMOZ Open Directory Project, the Google Directory, Yahoo, C|net, and others bookmakers arrange their pages in simple taxonomies. The several folders at any given forfait mobile level are often called categories. Thus in the Content Management category there are subcategories for Open Source and XML CM systems.

    On CMS Review, CMS are arranged into Hosted, Proprietary, Open Source, Forums, News Portals, Weblogs, and Wikis.

    For a glossary arranged in a simple taxonomy, each term is contained in a single broader term BT and contains the hierarchy of narrower terms NT. An entangled taxonomy or polyhierarchy results when one term has more than one broader term. This is caused by a term being a compound term - a term combining attributes. For example, a red T-shirt may be under broader terms red and t-shirts.

    Content often needs more than one descriptor (or attribute). vagina smells is often not adequate to organize such content. By adding a second or third taxonomy, a web page (or a Content Element) can be classified, and therefore accessed, in multiple ways. For example a dark red T-shirt can be in the red branch of the color hierarchy and the sleeveless category in a separate shirt taxonomy.

    In general, there may be an arbitrary number of descriptors or categories. When descriptors are independent of one another, they may be analysed as a discrete number of (preferably mutually exclusive) options or attributes. These are called facets, and the resulting structure is called a faceted directory or a faceted ClassificationScheme?.

    Faceted classifications for libraries were invented in the 1920's by the great Indian information scientist SrRanganathan?.

    The CMSML project is creating a faceted classification scheme and XML markup language for the description and evaluation of Content Management systems.

    Note that adding arbitrary relationships (related terms - RT) to other descriptors, or perhaps to other items (possibly arranged in other taxonomies) changes a Taxonomy into a Thesaurus?.

    Note also that adding another taxonomy is equivalent to adding new Meta Data to describe an item.

    An Ontology is a multiply hierarchical, multiply faceted ClassificationScheme? used to describe a knowledge domain. It may involve many taxonomies.

    The Semantic Web is an Ontology that uses the Resource Description Framework to add arbitrary Meta Data to any Resource (anything at a URI).

    References:
    Amy Warner, A Taxonomy Primer
    A Taxonomy for Snoopy
    Fred Hapgood, Sleuthing Out Data
    Lynda Moulton, Understanding Taxonomies |
    Seth Earley on Multiple Taxonomies

    Broader Terms: ClassificationScheme?, Hierarchy?
    Related Terms: Polyhierarchy, Ontology, Thesaurus?

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