Fora (Latin second declension, nominative plural
of 'forum') are places where people talk to each other online. They take several forms: email discussion lists, Usenet
[NNTP] newsgroups, Web-based Message Boards
, Bulletin Boards, Imageboards
, etc. Some fora are moderated, which means that one or more human "gatekeepers" must approve messages before posting in one form of moderation, or, in another, that certain users have the power to edit and delete postings and ban users.
As the majority websites now have forums as an integrated feature, rather than an exclusive focus, most examples can be found under Other Sites
See also Blog Tropes
and Wiki Tropes