A forum or message board is a means of communication over the internet that isn't as fast-paced as a chat room and is more organized and suited to build a community. To communicate with other members of the forum, threads are created. To these threads, replies can be made. Discussions are carried out in this way and are organized by the topic they were started in. Depending on the forum software installed at your community, a forum can house many forums organized by category on the forum index. Utilizing this, an administrator may designate a certain forum for a certain subject to organize his or her community better.
Threads usually have a point of interest to discuss, unless posted in the Pointless Post Palace or a similar forum for nonsense, and to derail a thread is frowned upon in most communities. If a thread is derailed or a dispute begins, a moderator may close the thread and members won't be able to discuss the matter further. Further penalties vary from community to community.