Now that you’re familiar with the basics of theme development, it’s time to start digging deeper into the world of themes. This section covers all of the basic theme functionality that you’ll need to consider while creating your theme:

• Custom headers – learn how to give your users the flexibility of adding their own header image
• Sidebars – add widgetized areas to your theme where users can add widgets
• Widgets – create re-usable PHP objects that can be added to a sidebar
• Navigation menus – register and display menus within your theme
• Taxonomy Templates – create templates for your taxonomy archive pages
• Pagination – work with WordPress’ built-in pagination
• Comments – customize the comments template
• Media – work with WordPress core’s media capabilities
• Featured Images & Post Thumbnails – work with and customize post thumbnails
• Post Formats – create different formats for displaying users’ posts
• Internationalization – learn how to prepare your theme for translation into different languages
• Localization – learn how to translate a WordPress theme
• Accessibility – learn about accessibility best practices to ensure everyone can use your theme
• Administration Menus – add menu items to the WordPress administration
• 404 Pages – create a custom 404 page

If you’re new to themes it’s worth working your way through each section, but you can also jump into a section if you’re looking for something specific.