news
Groups concerned with the news network, group maintenance, and software.
rec
Groups oriented towards hobbies and recreational activities
These "world" newsgroups are (usually) circulated around the entire Usenet—-this implies world-wide distribution. Not all groups actually enjoy such wide distribution, however. The European Usenet and Eunet sites take only a selected subset of the more "technical" groups, and controversial "noise" groups are often not carried by many sites in the U.S. and Canada (these groups are primarily under the talk and soc classifications). Many sites do not carry some or all of the comp.binaries groups because of the typically large size of the posts in them (being actual executable programs).
Also available are a number of "alternative" hierarchies:
alt True anarchy; anything and everything can and does appear; subjects include sex, the Simpsons, and privacy.
gnu
Groups concentrating on interests and software with the GNU
Project of the Free Software Foundation. For further info on what the
FSF is, FSF.
biz
Business-related groups.
Moderated vs Unmoderated
Some newsgroups insist that the discussion remain focused and on-target; to serve this need, moderated groups came to be. All articles posted to a moderated group get mailed to the group's moderator. He or she periodically (hopefully sooner than later) reviews the posts, and then either posts them individually to Usenet, or posts a composite digest of the articles for the past day or two. This is how many mailing list gateways work (for example, the Risks Digest).
news.groups & news.announce.newgroups