Usenet is one of the oldest parts of the Internet.
It consists of discussion groups called "newsgroups". Servers propagate messages in a peer-to-peer fashion. Clients connect to servers to read and post to newsgroups.
Access to Usenet is normally tolled. If you pay a fee, you may purchase real NNTP access to a Usenet server, and connect your own client software (and trade large files at binary groups). Many Usenet participants are stuck using free methods like http://groups.google.com to read and post.
The tree listed here is restricted to those groups, past or present, that have some substantial connection to NetHack. The full Usenet hierarchy is of course much vaster than this.
- net. (obsolete; see Great Renaming. All known versions of Hack were posted here)