This document is an introduction to Drupal theming, aimed at aspiring themers with a basic knowledge of HTML, CSS, and Drupal 6.x. It outlines essential theming principles, skills needed, and approaches to creating custom themes, emphasizing the importance of using .info files and template files without hacking core or contributed themes. Additionally, it covers the anatomy of themes, the Drupal theming engine, preprocessing functions, and the structure required for building a theme.