This site is built using Drupal, many themes from drupal.org plus some add-on modules for Drupal.

Configuration

Drupal lets you control the HTML used in content by changing input type for the content. There are three predefined input types. You can change the existing input types and create your own. The default input type allows the following HTML and is easily expanded.
<a> <em> <strong> <cite> <code> <div> <q> <blockquote> <ul> <ol> <li> <dl> <dt> <dd> <img>

This site has the following HTML elements added to save switching on a different type for normal content.
<h2> <h3> <h4> <h5> <h6>

Modules

Drupal is modular to give you the maximum options with the minimum code. You use only the bits you need. Read more about modules in Modules. The following modules are used in this site.

• Book constructs a book from pages
• Code Filter converts <code> elements to HTML.
• Meta tags lets you add meta tags for keywords and description.
• Pathauto automatically creates paths for nodes and vocabulary terms.
• Pet Meta inserts meta elements in the HTML head for accessibility.
• Search creates the site search box.
• Taxonomy is a Drupal core module that helps you categorize content.
• Tag Tool makes tag entry easier by displaying available tags.
• Token is required for Pathauto.

Themes

Answers

What is the best starting theme? Read Best Starting Theme.

How do you convert a theme from Drupal 5 to Drupal 6? Read Convert a Drupal 5 theme to Drupal 6.

How do you Create a theme step by step? Read Create a theme step by step.