Rules

Rules is an engine for automating actions in Drupal. Rules can react to events occurring on your site, such as a user logging in or a node being submitted, and it can perform customized follow-up actions such as redirecting to a certain page or sending email.

Rules is also a framework used by other modules, allowing them to expose user-reconfigurable components with sets of actions and conditions that are managed in easy to import/export configuration files. Rules leverages the Entity API to read and act on data and works seamlessly with all types of variables and entities.