Taxidermy puts a modern face on Drupal's taxonomy.module.
The goals of Taxidermy are simply to implement the improvements suggested for Taxonomy.module in D7 so that modules which implement the proposed hook_taxonomy_term_load, hook_taxonomy_term_insert, hook_taxonomy_term_update, and hook_taxonomy_term_delete can work on Drupal 6 and earlier. See the core issue to add proper taxonomy term hooks for more information about the goals of this module.
Various modules rely on hook_taxonomy's update and insert operations, but all of those modules have no shared mechanism for loading their additions on terms. Taxidermy module provides that functionality in a way that should be forward-compatible with Drupal 7.
This module doesn't do anything by itself. It has no user interface. It gives no output. It has no independent functionality.