The Sections module allows applying different themes to different pages in a Drupal site.

By default, Drupal doesn't allow the insertion of PHP codes in its pages. To embed PHP codes, you need to activate a Drupal module called PHP filter. By default, this module remains disabled.

There are three ways to interact with Drupal search system by implementing:

• nodeapi (update index)
• hook_search()
• hook_update_index()

Hooks are Drupal API code which allows module to interact with Drupal core. Its module system is based on the hooks concept.

Drupal integrates well with external search engines such as Xapian, Apache solr if the built-in search engine does not meet your needs properly.