UseNet

Before there were Message Boards, Wikis or the World Wide Web, before the Internet even existed in its present form, there was Usenet, one of the first distributed discussion systems around. Until the rise of Web-based forums after 2000, Usenet was the place to discuss things on the Internet, and quite a few tropes regarding message boards in general started here.

Usenet began in 1979, when programmers at Duke University realised that UNIX's uucp program, which was already being used to transfer email between sites, could also be used to transfer broadcast messages between sites (the original idea was to enable "community calendar"-style announcements, hence "news") and allow for discussion areas, which they decided to call "newsgroups". Eventually, as access to the Internet became more common, uucp was replaced by the Network News Transfer Protocol, and in 1985, the system itself was reorganised into 7 branches (the "Big 7") in an event called the "Great Renaming". An 8th, humanities, was added later.

The current Big 8 are:
 * comp: Computer science and IT discussions, including operating systems, hardware and applications.
 * humanities: Humanities (literature and fine arts) discussion.
 * misc: Anything that doesn't fit the other 7 categories, but mostly used for lifestyle discussions (groups include things like misc.kids and misc.consumers). misc.misc is often used as a test-message area.
 * news: Discussion about Usenet itself, including proposals for new newsgroups, anti-spam activism, etc.
 * rec: Recreational activities, hobbies, and sports discussion.
 * sci: Scientific discussion not related to computers, including math, engineering, physics, biology and astronomy.
 * soc: Sociology and culture-related discussions.
 * talk: Discussion of various controversial issues, such as evolution (talk.origins) and abortion (talk.abortion).

Outside the Big 8, but no less important:
 * alt: Usenet's equivalent to 4chan, right down to having 4chan's bad reputation; one old joke expands "alt" to "anarchists, lunatics and terrorists" due to the huge number of Single Issue Wonks and Cloudcuckoolanders that were (and, in several places, still are) present. Basically, anything goes here; topics range from serious discussions of technical issues that didn't fit inside the comp, sci or talk branches, to "vanity" newsgroups created as a one-off joke and now picking up nothing but spam, something that's been discouraged since the mid-1990s but still happens nonetheless. Just like 4chan, it includes many, many groups (specifically those under the alt.binaries.pictures sub-branch) solely dedicated to images -- and by images, we mean "porn". There used to be groups dedicated to pictures of all types, but the Web in general (and Google Image Search in particular) has made them obsolete. As for discussions, popular sub-branches include alt.tv, alt.religion and, of course, alt.flame (Usenet's equivalent to /b/).
 * Various regions and domains may have their own private or semi-private branches, such as vt (for Virginia Tech) or microsoft.public (Microsoft's official tech support forums).

Due to various legal and financial pressures (the former due to its use in copyright law violations; the latter because Usenet requires lots of bandwidth and storage space, more than its dwindling numbers of users can justify), Usenet has become less accessible over time. Many major internet providers have either limited access to Usenet, usually by refusing to carry alt.binaries, or have shut down their Usenet servers completely. To fill the gap, specialist Usenet providers have appeared, and many ISPs simply outsource Usenet access to them. Probably the easiest way to access usenet is through Google Groups, as awkward and buggy as it often is.

Given Usenet's oft-predicted imminent death, it's perhaps ironic that one of the most active Usenet groups of the 2010s is alt.obituaries, where obituary writers and fans hang out.

Usenet in fiction

 * The galaxy-spanning communications network in Vernor Vinge's A Fire Upon the Deep is modelled on Usenet, and the idiosyncratic writing styles of some of the characters are inspired by some of Usenet's regular contributors back in the day.
 * The Legion of Net Heroes was created on Usenet, and still lives on the newsgroup rec.arts.comics.creative. A lot of early LNH characters have usenet-based gimmicks and powers, such as Sig.Lad and Dr. Killfile. The LNH cosmology is also based on usenet; each newsgroup is an alternate dimension and characters often travel between them.