Taxonomy refers to a generic structure or classification system into which items may be classified based on units referred to as taxa (singular taxon). A scientist specializing in taxonomy is known as a taxonomist. The term taxonomist is usually associated with Linnaean taxonomy.
In biology, the practice of classifying organisms into a hierarchical structure based on relatedness. This is more accurately referred to as Linnaean taxonomy due to the use of the term in many other fields.
In the field of information science, taxonomy is used for the practice of creating information structures for classifying documents, objects, concepts, or anything else that can have metadata attached to it. These structures are generally hierarchical, but can be polyhierarchical (having multiple inheritance lines) or even based on a network model.
Taxonomy as a concept and practice has been imported to many other fields. One of the better known examples is Bloom's taxonomy, created by Benjamin Bloom, an educational psychologist, in the 1950's that classifies levels of intellectual behavior important in learning. The lowest level, requiring the least intellectual exertion, is simple recall of information.