Newsgroups are the system by which the text and binary content on Usenet is arranged. They are comparable to discussion groups on the Internet, or the Dewey decimal system in your library. Presently, there are actually greater than 110,000 newsgroups on Usenet, despite the fact it usually no more than 20,000 are active. Each newsgroup is dedicated to a unique topic. Let's look at a generic situation to help demonstrate:
A member in New York has a question on Topic B and posts this question on a newsgroup focused on Topic B. A person in Paris posts what he or she believes to be the answer to the New Yorker's challenge. A different user in Germany proposes another option that he/she believes is more accurate.
Because of illustrations like this, you can see how Usenet newsgroups are often invaluable for research. Other people with the exact same issue as the New Yorker can later find the same dialogue and do not have to re-post the issue.
So, how are newsgroups organized? Newsgroups are organized in a hierarchal manner. One can find eight major hierarchies employed (known as the "Big 8"):
|Comp.*||Discussion of computer-related topics|
|News.*||Discussion of Usenet itself|
|Rec.*||Recreational activities (i.e. games and hobbies)|
|Talk.*||Discussion of controversial issues such as politics and religion|
|Humanities.*||Literature, philosophy, etc.|
|Misc.*||Anything which doesn't fit in any of the other hierarchies|
At the time these hierarchies were first created, discussions about recipes, drugs and sex were not allowed in any of the hierarchies. This minor oversight resulted in the advent of the alt.* (abbreviation of "alternative") Usenet hierarchy. Due to the fact this new hierarchy was not part of the original Big 8, the policies pertaining to creation of a new newsgroup in the alt.* branch were more relaxed and this hierarchy rapidly increased in size.
Usenet newsgroups were initially developed in order to share text files, but they proved quite effective for distributing binary files after a handful of technical difficulties had been addressed. First, binary data were converted to text characters (by way of Uuencode, Base64, and yEnc) so they could be transmitted. Next, most newsgroup hosts limited the size of specific posts to newsgroups. To contend with this, binary files were divided into smaller files by newsreaders. A newsreader at the receiving end then put the smaller files back together into the original binary file. Binary files are mostly distributed under alt.binaries.*.
This splitting apart of binary files has heightened the importance of completion rates and retention rates. Completion rates are the percentage of a file that is recovered by a newsreader. If one file portion is lost, it may not be possible to reassemble the binary file. The top Usenet providers boast completion rates of 99% or greater. Retention rates are the period for which a newsgroup server will host a file before it is erased. A retention rate "war" has come to pass among the most popular Usenet providers.
As you have seen, newsgroups provide a means of coordinating the massive volume of information that exists on Usenet. With the number of newsgroups offered, it is almost guaranteed that everyone will find a newsgroup of interest. Happy searching!