Community documentation for Drupal 8: general Drupal topics, contributed projects documentation.
Curated introduction to readers new to Drupal 8.
Documentation for developers about tools, processes, and standards that is not specific to a major version of Drupal.
Community documentation for Drupal 7: general Drupal topics, contributed projects documentation.
The Drupal.org Community Documentation is maintained by the Drupal community. Find out how you can help.
Search the complete Drupal API including forms, menus, node access, theme system, etc.
Use git for version control to manage projects and code, and to colloborate with other Drupal developers.
Examine a standard repository of sample modules that can be used to learn module development, or are referenced on handbook pages.