BuddyPress.org

BuddyPress.org uses bbPress, the same forum software that comes with the BuddyPress download. However, the forums on BP.org are site-wide forums (using an external install method) and are skinned to look like the rest of the site. They are not group-based forums as you get with a standard install of BuddyPress.

To learn more about external bbPress installs, read this:

https://buddypress.org/forums/topic/create-a-site-forum#post-36466