Is this really the version you are looking for? Kentico 8 documentation is no longer updated. Use the switch in the header to choose your Kentico version.

Message boards

The Message boards application enables site visitors to comment on the content of a particular page. Each message board is related to a document on which it is placed, and optionally to a user or group. Messages can be moderated by board moderators. Users can subscribe to receiving notifications about new messages and rate the content of the document.

Message boards provide similar functionality to the Forums application. However, unlike structured forums, message boards are flat and simpler.