Early Internet forums could be described as web versions of newsgroups or electronic mailing lists; allowing people to post messages and comment on other messages. Later developments emulated the different newsgroups or individual lists, providing more than one forum, dedicated to a particular topic. At first, Internet forums had the same structure as a guestbook or mailing list, but the Ultimate Bulletin Board software, created in 1996, invented a table-based layout that evolved into the designs used in modern software such as vBulletin and phpBB. In Japan, 2channel's style had a similar effect on the layouts of other Japanese boards.

As of late, forum software developers have actively encouraged the creation of open source plugins which can be integrated with the software as a means of expansion. Generally, these plugins provide more interaction for users and may add special features to the forum software.



source:http://en.wikipedia.org/wiki/Internet_forum