If you aren’t already following along, I highly recommend checking out the How To Create A WordPress Theme tutorial series by Ian Stewart (ThemeShaper.com). This 12-part series (8 complete at the time of this writing) aims to take you from nothing to a fully functional, semantically rich, flexible WordPress theme in digestible chunks. Along the way, Ian describes the changes being made, and why you are making them. In this way, you can gain a basic understanding of the roles of the various theme template files, and the code contained within them.

The lesson is broken down thusly:

1. Introduction
2. Theme Development Tools
3. Creating a Theme HTML Structure
4. Template and Directory Structure
5. The Header Template
6. The Index Template
7. The Single Post, Post Attachment, & 404 Templates
8. The Comments Template
9. The Search Template & The Page Template
10. The Archive, Author, Category & Tags Template
11. The Sidebar Template
12. Reset-Rebuild Theme CSS & Define Your Layouts

If you’ve ever thought about creating your own theme, but felt like the task was too big to tackle, this series of articles is for you. It’s a great bit of instruction that will introduce you to the core pieces of WordPress theming without overwhelming you or trying to cram too much into a single article.

Props, Ian!