Classification

Classification is any of a variety of related activities that assign classes. The simplest example is to allocate objects to a pre-existing set of two or more classes or categories. This is distinct from the problem of establishing what the classes themselves ought to be, perhaps through a form of cluster analysis.^[1] Examples of binary classifications include many medical diagnoses, identifying spam emails and deciding whether to give someone a driving licence.

Classification is a part of many different kinds of activities and is studied from many different points of view including medicine, philosophy, law, anthropology, biology, taxonomy, cognition, communications, knowledge organization, psychology, statistics, machine learning, economics and mathematics.

As well as 'category', synonyms or near-synonyms for 'class' include 'type', 'species', 'order', 'concept', 'taxon', 'group', 'identification' and 'division'.

The meaning of the word 'classification' (and its synonyms) may take on one of several related meanings. It may encompass both classification and the creation of classes, as for example in 'the task of categorizing pages in Wikipedia'; this overall activity is listed under Taxonomy. It may refer exclusively to the underlying scheme of classes (which otherwise may be called a taxonomy). Or it may refer to the label given to an object by the classifier.