While Drupal by now comes with plenty of themes out of the box, the real power comes with a level of customization obtainable for any site or brand. Prior to learning how to create a custom theme for Drupal, you will require to be known with what’s already present, and what makes a good theme. The official listing of Themes for Drupal is obtainable on drupal.org. You can click on the Themes Page. They are hundreds of Themes available for Drupal through its official site. Themes are made up of basic PHP, CSS and XHTML. Themes can be flexible and have things like Sidebars go away when there's no content allotted to them. On the web there are many themes available, and there is one site, themesgarden.org, that lets you test-drive a multitude of themes available for Drupal. If you can click on the Preview link for Slate, you can view that there is lot of flexibility, as the displayed areas are the parts that we can allot content to. That’s in fact what makes a good theme flexible. You might want to take a minute to gloss over the Themes obtainable on Drupal.org and see what other people created, to get some concepts when you develop your own Drupal Theme.