Comments
From MoodleDocs
Basic Features
Comments anywhere
Comments 2.0 implemented consistent interface for comments everywhere in Moodle 2.0, a new comment block is introduced, it can be added to all Moodle pages, so users can easily add comments on the page.
Ajax interface
The new comments interface uses Ajax to load/add comments without refresh current page, it is easy to use and consistent in Moodle.
Flexible capabilities
Administrators are able to control if the user can see or use the comments block based on the context.