Customise Drupal 7 Taxonomy View / Template (without module)
As described in Drupal 7 Theme Hook Suggestions, the template files that Drupal looks for a taxonomy term page are the following:


taxonomy-term--[tid].tpl.php
taxonomy-term--[vocabulary-machine-name].tpl.php
taxonomy-term.tpl.php


Replace [tid] with the taxonomy term ID, and [vocabulary-machine-name] with the machine name set for the vocabulary. Supposing that the machine name is programming_languages, then the template filename that Drupal looks is taxonomy-term--programming-languages.tpl.php. (The underscores are replaced with hyphens.)

The first file that is found is the one that Drupal uses.