What taxonomy is all about
It's helpful to think of taxonomy as the use of "categories". In fact, this is what it was called in earlier versions of Drupal. Taxonomy lets you gather together content under one term or another. It has become advanced enough to give you as much flexibility as you need in designing classification schemes.
The first step in establishing a taxonomy is creating a new Vocabulary. Next you provide the terms that fall within that Vocabulary. The arrangement can be "flat," as in a tagging system, or hierarchical, with parents and children.
Here's how you might create a taxonomy for a site arranged by musical genre:
- Vocabulary = Music
- term = classical
- sub-term = concertos
- sub-term = sonatas
- sub-term = symphonies
- term = jazz
- sub-term = swing
- sub-term = fusion
Sometimes you will want to create a "controlled vocabulary," where content authors can assign terms but they have been predetermined. If so, you will need to add those terms to your vocabulary, in advance.
An alternative model for organizing information is the use of "tags". User-defined tags can be added to Drupal content on-the-fly. In Drupal 7, a ready-to-use "Tags" vocabulary is included by default, so users can immediately begin adding tags to their content.
By using multiple vocabularies it is possible to classify an individual node in many ways. For example, a node representing a musical work might have a genre vocabulary and a time-period vocabulary (including terms such as: seventeenth century, eighteenth century). The node might also be identified using the genre vocabulary term, such as "sonata". Adding a vocabulary for "composers", might lead to the the following combination of terms: as an "early-eighteenth-century" "sonata" by "Bach", and it could be located by any of these three terms.