newsgroup n. [Usenet] One of {Usenet}'s huge collection of topic groups
   or {fora}. Usenet groups can be `unmoderated' (anyone can post) or
   `moderated' (submissions are automatically directed to a moderator, who
   edits or filters and then posts the results). Some newsgroups have
   parallel {mailing list}s for Internet people with no netnews access,
   with postings to the group automatically propagated to the list and vice
   versa. Some moderated groups (especially those which are actually
   gatewayed Internet mailing lists) are distributed as `digests', with
   groups of postings periodically collected into a single large posting
   with an index.

   Among the best-known are comp.lang.c (the C-language forum), comp.arch
   (on computer architectures), comp.unix.wizards (for Unix wizards),
   rec.arts.sf.written and siblings (for science-fiction fans), and
   talk.politics.misc (miscellaneous political discussions and {flamage}).


Source: The Jargon File