Drupal

APIReference / DescriptionLinkVisit
Official documentationhttps://api.drupal.org/api/drupalGo
HooksAllow modules to interact with the Drupal core.https://api.drupal.org/api/drupal/includes%21module.inc/group/hooks/7Go
Database abstraction layerAllow the use of different database servers using the same code base.https://api.drupal.org/api/drupal/includes%21database%21database.inc/group/database/7Go
Menu systemDefine the navigation menus, and route page requests to code based on URLs.https://api.drupal.org/api/drupal/includes%21menu.inc/group/menu/7Go
Form generationFunctions to enable the processing and display of HTML forms.https://api.drupal.org/api/drupal/includes%21form.inc/group/form_api/7Go
File interfaceCommon file handling functions.https://api.drupal.org/api/drupal/includes%21file.inc/group/file/7Go
Field APIAttach custom data fields to Drupal entities.https://api.drupal.org/api/drupal/modules%21field%21field.module/group/field/7Go
Search interfaceThe Drupal search interface manages a global search mechanism.https://api.drupal.org/api/drupal/modules%21search%21search.module/group/search/7Go
Node access rightsThe node access system determines who can do what to which nodes.https://api.drupal.org/api/drupal/modules%21node%21node.module/group/node_access/7Go
Theme systemFunctions and templates for the user interface to be implemented by themes.https://api.drupal.org/api/drupal/modules%21system%21theme.api.php/group/themeable/7Go
Constantshttps://api.drupal.org/api/drupal/constants/7Go
Globalshttps://api.drupal.org/api/drupal/globals/7Go
Form API Referencehttps://api.drupal.org/api/drupal/developer%21topics%21forms_api_reference.html/7Go