For most people (except public personalities, journalists...) before the rise of the Internet, speaking publicly never involved more than a few dozen persons listening and possibly answering. The evolution of communication, and mostly the emergence of the Internet, opened a lot of new possibilities to communicate with plenty of people at the same time. When saying this, one might be thinking about blogs, but they have one main drawback: they are mainly unidirectional. And way before the apparition of the first blogs, even before the apparition of the Internet, there was a way of exchanging ideas with a lot of people at the same time, called Usenet.
It is somewhat counter-intuitive to mention Usenet in a post talking about “new media”. But it has really had a big impact on how people were communicating inside communities. Launched in 1980, it quickly gained some attention, and by 1983 it already had more than 500 clients connected to the network, allowing everyone with an access to these machines to discuss with thousands of people at the same time. It continued growing for two decades, but has been mostly replaced by Web-based forums at the beginning of the 21th century.
However, we can safely say that it was the first very successful implementation of the concept of forum, with categories organized in a tree-like structure, relatively long retention of messages allowing asynchronous communication and longer, more qualitative posts compared to later instant messaging.
Although Usenet servers mostly ran using Internet connections, in its early history Usenet used to work on various networks that supported the UUCP (Unix to Unix copy) protocol, like Arpanet. Every server had its own copy of all the messages of the boards it was following, making the network decentralized and resilient, but also enabling people with local communication links to discuss easily with people all around the world.
It has been one of the main way of sharing and discussing ideas on the Internet until they were replaced by forums.
However, as the World Wide Web became popular in the 90s, a new type of open discussion platform appeared, taking advantage of the dynamic and graphical capabilities of the Web: it was the birth of forums as we (more or less) know them today. They kept a very similar organization to Usenet, with different boards containing discussions grouped by topics, though they are quite different from a technical point of view. Instead of having one portal for all of the possible topics, plenty of different forums appeared, most of the time focusing on only one topic. On the other hand, for each forum, posts are centralized on one single server, unlike Usenet. Forums add some features that weren’t on Usenet, such as text formatting, hyperlinks, images… or in other words, everything that made the Web surpass its predecessors or competitors. The last big thing that web forums brought is the possibility of navigating without the need of any special software; a browser is enough.
That said, in my opinion web forums are just an evolution of online discussion platforms to fit the standards of the Web, but they serve the same purpose (putting aside the binary sections of Usenet). Just like the Web or Linux were announced on Usenet, for example, Bitcoin was announced on web forums.
Nowadays, despite plenty of forums being slightly deserted, a lot of them are still very active, proving that this format of web discussion platform is still a good solution for people wanting more space to develop their ideas compared to social networks or instant messaging tools.
This one is a bit special, but I think it may be interesting to quickly mention it: Reddit has undeniably gained a lot of popularity while forums became less and less used. The debate about whether it is a forum or not is not settled, and for good reasons. It doesn’t have the tree-like organization of previous forums, but still has a lot of different boards where posts are grouped by topic; it makes extensive use of voting on posts, and consequently posts aren’t displayed from the most recent to the older by default, but also according to their popularity.
The platform still offers the possibility to write lengthy and argumentative posts, ordered in a threaded way, similarly to classical forums, but most people agree that it doesn’t favour long discussions as much as old-fashioned forums. So, while it’s a quite different type of medium compared to usual forums, it has a lot of common with them, and is nowadays one of the main places for public discussion, that can be considered as an evolution taking into account the trends going on in other media (e.g. social media).
https://archive.org/details/byte-magazine-1983-10/page/n219/mode/2up?view=theater
https://web.archive.org/web/20080919131748/http://www.alea.net/usenet/outils/stats/
https://www.quora.com/Is-Reddit-the-best-modern-implementation-of-an-internet-forum#:~:text=Reddit%20is%20several%20different%20forums,separated%20communities%20like%20subreddits%20are
https://www.quora.com/Did-Reddit-kill-forums
https://www.reddit.com/r/TheoryOfReddit/comments/12gx1h/reddit_is_not_a_forum/