phpBB is an open source bulletin board software package. It is a web-based application written in PHP and is used to create and manage a variety of discussion forums and bulletin boards. phpBB allows users to create topics, reply to existing topics, attach files, and edit posts. It also has user-friendly features such as a search engine, private messaging, user groups, a user ranking system, custom themes and styles, and an extensive plugin system that allows users to customize their forums with a variety of additional features and functions. phpBB is a great solution for businesses and enterprises that need to create a community and get their customers engaged with discussions and conversations.
More of a comment system than the categorized forum.
Better looking, faster and simpler.
It is very similar to the way phpBB works, however, it is less compatible and more difficult to install.
Discontinued Last launched 4 years ago. Last engagement 2 years ago.
Beautiful interface, uses modern PHP and AJAX functions. Uses BCRYPT for password storage, unlike many others who seem to think that md5 and sha1 are still safe for password storage (*cough* smf, mybb, fluxbb, punbb).
Discourse
Flarum
MyBB
Simple Machines Forum
FluxBB
NodeBB
bbPress
vBulletin
XenForo
Invision Community
PunBB
ZeroTalk
Vanilla
WoltLab Suite
AsmBB
YaBB
TangoBB
C-BOARD
miniBB
IkoBB
It is more of an online messenger than a cms forum.