Most importantly, you should already be familiar with the most current stable version of WordPress. You should understand how to add content to the WordPress blog system and how its posts, categories, static pages, and subpages work. Understanding the basics of installing and using plugins will also be helpful (though we will cover that to some extent in the later chapters of the book as well).

Even if you'll be working with a more technical WordPress administrator, you should have an overview of what the WordPress site that you're designing entails, and what (if any) additional plugins or widgets will be needed for the project. If your site does require additional plugins and widgets, you'll want to have them handy and/or installed in your WordPress development installation (or sandbox—a place to test and play without messing up a live site). This will ensure that your design will cover all the various types of content that the site intends to provide.

I'll be giving detailed explanations of the CSS rules and properties used in this book, and the "how and why" behind those decisions. You should know a bit about what CSS is, and the basics of setting up a cascading stylesheet and including it within an XHTML page. You'll find that the more comfortable you are with CSS markup and how to use it effectively with XHTML, the better will be your WordPress theme-creating experience.

You don't need to have every markup tag in the XHTML standard memorized. (If you really want, you can still switch to the Design view in your HTML editor to drop in those markup tags that you keep forgetting—I won't tell). However, the more XHTML basics you understand, the more comfortable you'll be working in the Code view of your HTML editor or with a plain text editor. The more you work directly with the markup, the quicker you'll be able to create well-built themes that are quick loading, semantic, expand easily to accommodate new features, and are search engine friendly.

You definitely don't have to be a PHP programmer to get through this book, but be aware that WordPress uses liberal doses of PHP to work its magic! A lot of this PHP code will be directly visible in your theme's various template files. PHP code is needed to make your theme work with your WordPress installation, as well as make individual template files work with your theme.

If you at least understand how basic PHP syntax is structured, you'll be much less likely to make mistakes while retyping or copying and pasting code snippets of PHP and WordPress template tags into your theme's template files. You'll be able to more easily recognize the difference between your template files, XHTML, and PHP snippets so that you don't accidentally delete or overwrite anything crucial.

If you get more comfortable with PHP, you'll have the ability to change out variables and call new functions or even create new functions on your own, again infinitely expanding the possibilities of your WordPress site.

If your project will be incorporating any other special technologies such as JavaScript, AJAX, or Flash content, the more you know and understand how those scripting languages and technologies work, the better it is for your theme-making experience (again W3Schools.com is a great place to start).