Taxonomy: categories and classification schemes Drupal 4.7 The taxonomy module is one of the most popular features because users often want to create categories to organize content by type. Users also use categories to help in site navigation. The taxonomy module can automatically classify new content, which is very useful for organizing content on-the-fly. A simple example would be organizing a list of music reviews by musical genre. Taxonomy is also the study of classification. The taxonomy module allows you to define vocabularies (sets of categories) which are used to classify content. The module supports hierarchical classification and association between terms, allowing for truly flexible information retrieval and classification. The taxonomy module allows multiple lists of categories for classification (controlled vocabularies) and offers the possibility of creating thesauri (controlled vocabularies that indicate the relationship of terms) and taxonomies (controlled vocabularies where relationships are indicated hierarchically).