"sci" Discussions marked by special and usually practical
knowledge, relating to research in or application of the
established sciences.
"misc" Groups addressing themes not easily classified under any
of the other headings or which incorporate themes from
multiple categories.
"soc" Groups primarily addressing social issues and socializing.
"talk" Groups largely debate-oriented and tending to feature long discussions without resolution and without appreciable amounts of generally useful information.
"news" Groups concerned with the news network and software
themselves.
"rec" Groups oriented towards hobbies and recreational
activities.
Also available are many "alternative" hierarchies, like:
"alt" True anarchy; anything and everything can and does appear. Subjects include sex, and privacy.
"biz" Business-related groups
"clari" Newsgroups gatewayed from commercial news services and other 'official' sources. (Requires payment of a fee and execution of a licence. More information by email to info@clarinet.com).