News Groups News groups are a bit different. These, in turn, send the article on to other servers, until it's made its way to all news servers that carry that group. This can take a few days. This lets you easily focus on the discussions that you care about, and ignore everything else. Post your thoughts for all to see, and come back later to find 27 clueless replies and, perhaps, one insightful comment.
Moderated groups can be better, but much depends on the quality and speed of the moderator.
Each message may have several replies. Each reply can in turn have its own replies, and so on. Because there is no Big List of all boards the way there is with newsgroups, the boards may suffer from less of the spamming and general obnoxiousness that newsgroups suffer from. Conversely, the user interface on the typical newsreader is a lot better than the user interface on the typical Web board. Also, because there is no Big List of all boards, the only people in the discussion will be those who were invited or who found a link to it.