A successor to Usenet, a message board is a kind of web browser-based forum designed to facilitate ongoing conversations. Typically, there will be a list of "threads" of conversation, each of which can have multiple posts. Threads are usually sorted by the date-time stamp of the last post so that the threads with the most recent activity will be at the top, though any "sticky" threads will be listed above any non-sticky threads.
Message Boards that existed before the Web (you had to dial a different number for each server) are known as Bulletin Board Systems or BBS. Those that still exist use e-mail or telnet protocols. The terms Bulletin Board and Message Board are basically interchangeable now, however.
A Message Board can be very easy and inexpensive (even free) to set up, and can have an elaborate structure of sub-boards, so most any communal interest can have its own place (or more likely places) for discussions. They can be set up to be very open or very exclusive: either open to unregistered posters, closed to unregistered posters but with fully automated registration, or even requiring administrator approval of registration. They can also have as many different styles of moderation as there are personalities.
As a medium, message boards lend themselves to short works, such as brief critical analysis, capsule reviews, and compressed fanfic. They're most useful for interactive works, such as Play-by-Post Games. Longer works are typically better served by other media, especially where in-line interactivity is not a requirement.
- The TV Tropes Fora is a message board.
- The term "Image Macro" apparently originated on the Something Awful forums.
- Rich Burlew's Giant in the Playground forums, associated with his Order of the Stick webcomic and now also Balder & Noguchi's Erfworld, is an example of extensive rules and strict moderation. It also contains a high concentration of tropers.
- Gaiaonline is one of if not the largest forums on the internet. It began as a simple anime/roleplaying message board and link list but has exploded into a community with millions of members.
- This is, of course, Older Than They Think as you can see here. 2000 years ago, people were insulting each other's mothers, each others sexualities, and bragging just like they are now. So, oddly, this is Older Than Feudalism.
- The word "forum" itself has similar origins, but was used to refer to a discussion group long before the internet.