Crossposting
Crossposting
means sending your article to several groups all
at once; a single copy of your article is propagated across
the net and is referenced from within any of the groups in
the Newsgroups: line. Crossposting saves resources (because
only one copy of the article is sent and stored), and saves
human energy (because most software is smart enough to show
it only once to readers unless they explicitly ask to see it
again).
Note that crossposting articles can fall under the category
of malicious or wanton flooding of newsgroups, forbidden under
Rule 9.
Spamming is the term for posting an article individually
to different newsgroups instead of crossposting it.