| drupal/ modules/ system/ system.install | @todo Start this series of updates at 2000. |
| Database abstraction layer | drupal/ includes/ database.inc | Allow the use of different database servers using the same code base. |
| File interface | drupal/ includes/ file.inc | Common file handling functions. |
| Form generation | drupal/ includes/ form.inc | Functions to enable the processing and display of HTML forms. |
| Formatting | drupal/ includes/ common.inc | Functions to format numbers, strings, dates, etc. |
| Hook implementations for user-created content types. | drupal/ modules/ node/ node.module | |
| Hooks | drupal/ includes/ module.inc | Allow modules to interact with the Drupal core. |
| Input validation | drupal/ includes/ common.inc | Functions to validate user input. |
| Menu system | drupal/ includes/ menu.inc | Define the navigation menus, and route page requests to code based on URLs. |
| Node access rights | drupal/ modules/ node/ node.module | The node access system determines who can do what to which nodes. |
| Pathauto: Automatically generates aliases for content | contributions/ modules/ pathauto/ pathauto.module | The Pathauto module automatically generates path aliases for various kinds of
content (nodes, categories, users) without requiring the user to manually
specify the path alias. This allows you to get aliases like
/category/my-node-title.html instead of... |
| Search interface | drupal/ modules/ search/ search.module | The Drupal search interface manages a global search mechanism. |
| Themeable functions | drupal/ includes/ theme.inc | Functions that display HTML, and which can be customized by themes. |
| XML Sitemap | contributions/ modules/ xmlsitemap/ docs/ xmlsitemap.php | Notify search engines of site updates. |
