Introduction to Rules

Rules are reconfigurable micro-programs that can run at the click of a button or as a reaction upon any detected situation. Site builders and module developers can configure various actions and control sequences that will then be fired in simple or complex sequences.

Rules can react immediately or be scheduled to run in the future. Large operations and those that make sense to background can also be queued using the Rules Scheduler. Another existing approach is to use Views Bulk Operations' Queue API integrations.

The Rules project includes:

• A rule-based, event-driven, action evaluation engine
• Extensible data type support and data lists support
• Wrappers for Drupal's hooks as actions, conditions, and events
• A general configuration interface, the Rules Admin UI
• An API for building forms by exposing user-configured/controlled rules

Configuring Rules through the UI

If the Rules UI module is enabled, you can configure the rules at:
(Drupal 7/8) Administration » Configuration » Workflow » Rules (/admin/config/workflow/rules).
(Drupal 6) Admin » Rules (/admin/rules).
If you've just installed Rules UI and don't see it there, be sure to clear your caches.