CComment docs
What is it all about
CComment is Joomla component, which allows you add comment functionality to your Joomla website. Comments can be added to the default Joomla content extension (articles) or to any other Joomla component for which a CComment plugin exists. The current non-exclusive feature list of the CComment includes:
Ajax-based
Spam protection
Plugins for 3rd party components
Nested comments
Multilingual support
Import function
UBB code support, image support, emoticon support, quote support
Community Builder, Jomsocial, K2 avatar support & Gravatar support
Allow comments per category
Show comment count on front page
Front-end comment moderation
RSS-feed
E-Mail notifications of new comments (with unsubscribe options)
Publish/unpublish of comments with one click in the link of a mail for moderators