A Newsgroup loosely defines a subject for the posts / discussions that are associated with it within Usenet. For instance discussions found under talk.philosophy.metaphysics would be related to the metaphysical and posts found in alt.binaries.multimedia.horror are generally horror movies. So if you're interested in talking about metaphysics or watching Return of the Living Dead (which was recently posted) then you're covered.

Newsgroups follow a structured, hierarchic and taxonomic naming structure. The newsgroup names have a two-fold purpose:

  1. To provide a means for users to find groups of interest to them.
  2. To assist site administrators in managing their systems.

Each part of a newsgroup name can be up to 14 characters long and can consist only of letters, digits, "+" and "-", with at least one letter. Those parts are divided by dots. The separate parts of the names provide for the hierarchic structure. The first part of the name is the most general and each level gets more specific until you reach the full name describing the newsgroup; I don't think there is a limit to the number of levels a name can contain as long as it follows the other rules. There are 8 main top-level sections considered to be the 'heart' of the newsgroups:

Those main categories are considered the "Big Eight" probably mostly for historical reasons. There are about 57 other main top level categories and probably tons of other smaller or unknown groups run by local sites. Lists of widely propagated groups are periodically posted to 'news.lists.misc'. There are a lot of country / language specific groups such as ca (Canada) and it (Italy / Italian). Another large group would probably be the alt.binaries groups.

These names are inclusive, as opposed to definitive. They define a certain area a message can be posted to if there isn't a better fit available. They define general areas, not limits.

To create a new newsgroup, there are important guidelines to follow. The guidelines are 'official' in that they are widely distributed and widely adhered to. Other than that, any site admin can create any group they want, and any site admin can choose to propagate or not propagate any group they see fit.

"If you have a good newsgroup idea, then read 'news.groups' for at least six months to find out how things work. If you're too impatient to wait six months, then you really need to learn; read 'news.groups' for a year instead."

- What is Usenet?

The creation of a new group is a pretty serious affair on Usenet. If you want your group to be widely propagated in the community you have to follow this general process:

  1. Request a discussion for the creation of a new newsgroup in 'news.groups'. This is where proponents of the group can agree on a name and charter for the new group.

  2. After the discussion period, a call for votes is posted to 'news.announce.newgroups'. The voting process is handled by a volunteer group, called Usenet Volunteer Votetakers (UVV).

  3. The final tally has to reflect that there were 100 more YES/create votes than NO/don't create votes AND that at least 2/3 of the votes were in favour, then a new group creation control message will be sent out. If either of these conditions is not met then the group is not created, and can re-apply for a vote no sooner than six months after the voting process.