What is Usenet Service?
Usenet is a world-wide distributed discussion system. It consists of a set of "newsgroups" with names that are classified hierarchically by subject. "Articles" or "messages" are "posted" to these newsgroups by people on computers with the appropriate software -- these articles are then broadcast to other interconnected computer systems via a wide variety of networks. Some newsgroups are "moderated"; in these newsgroups, the articles are first sent to a moderator for approval before appearing in the newsgroup. Usenet is available on a wide variety of computer systems and networks, but the bulk of modern Usenet traffic is transported over either the Internet or UUCP.
Why Is It Hard To Define Usenet?
The first thing to understand about Usenet is that it is widely misunderstood. Every day on Usenet, the "blind men and the elephant" phenomenon is evident, in spades. In my opinion, more flame wars arise because of a lack of understanding of the nature of Usenet than from any other source. And consider that such flame wars arise, of necessity, among people who are on Usenet. Imagine, then, how poorly understood Usenet must be by those outside! Any essay on the nature of Usenet cannot ignore the erroneous impressions held by many Usenet users. Therefore, this article will treat falsehoods first. Keep reading for truth. (Beauty, alas, is outside the scope of this article.)
What Usenet Is?
Usenet is the set of people who exchange articles tagged with one or more universally-recognized labels, called "newsgroups" (or "groups" for short). There is often confusion about the precise set of newsgroups that constitute Usenet; one commonly accepted definition is that it consists of newsgroups listed in the periodic "List of Active Newsgroups" postings which appear regularly in news.lists.misc and other newsgroups. A broader definition of Usenet would include the newsgroups listed in the article "Alternative Newsgroup Hierarchies" (frequently posted to news.lists.misc).
An even broader definition includes even newsgroups that are restricted to specific geographic regions or organizations. Each Usenet site makes its own decisions about the set of groups available to its users; this set differs from site to site. (Note that the correct term is "newsgroups"; they are not called areas, bases, boards, bboards, conferences, round tables, SIGs, echoes, rooms or usergroups! Nor, as noted above, are they part of the Internet, though they may reach your site over it. Furthermore, the people who run the news systems are called news administrators, not sysops. If you want to be understood, be accurate.)