Drupal Commons is a ready-to-use solution for building either internal or external communities. It provides a complete social business software solution for organizations.
Drupal Commons helps organize content into topic (organic) groups with blog, discussion, document, wiki, and event content types. It also allows users to create (user) relationships with each other in order to follow each other's activities on a site. Authenticated users can view a personalized dashboard containing content from all their subscribed groups.