What is Usenet? How Does it Work?
One of the most fabulous facts about Usenet is that it is not part of any organization, or has any sort of centralized network management authority. In fact, it is part of Usenet lore that except for a technical description, you cannot define what it is; you can only say what it is not.
At the risk of sounding stupid, one might define Usenet as a collaboration of separate sites who exchange Usenet news. To be a Usenet site, all you must do is find another site Usenet site, and strike an agreement with its owners and maintainers to exchange news with you. Providing another site with news is also called feeding it, whence another common axiom of Usenet philosophy originates: “Get a feed and you are on it.”
Articles are submitted to one or more newsgroups. One may think about a newsgroup a forum for articles relating to a common topic. All newsgroups are organized in a hierarchy, with each group’s name indicating its place in the hierarchy. This often makes it easy to see what a group is all about. For example, somebody can see from the newsgroup name that comp.os.linux.announce is used for announcements concerning a computer operating technique named linux.
The basic unit of Usenet news is the article. This is a message a user writes and “posts” to the net. In order to enable news systems to deal with it, it is prepended with administrative information, the so-called article header. It is similar to the mail header format laid down in the Web mail standard RFC-822, in that it consists of several lines of text, each beginning with a field name terminated by a colon, which is followed by the field’s value.
These articles are then exchanged between all Usenet sites that are willing to carryover news from this group. When one sites agree to exchange news, they are free to exchange whatever newsgroups they like to, and may even add their own local news hierarchies. For example, groucho.edu might have a news link to barnyard.edu, which is a major news feed, and several links to minor sites which it feeds news. Now, Barnyard College might get all Usenet groups, while GMU only wants to carryover a few major hierarchies like sci, comp, rec, etc. A number of the downstream sites, say a UUCP site called brewhq, will need to carryover even fewer groups, because they don’t have the network or hardware resources. On the other hand, brewhq might need to get newsgroups from the fj hierarchy, which GMU doesn’t carryover.