Established in 1980, Usenet is a system of distributed servers that relay messages (termed "posts" or "articles", and collectively "news") related to categories (termed newsgroups). Posts are viewed in the same way as threads on forums or BBSs, but posts are stored on the server(s) individually and sequentially.
Usenet servers use a flooding algorithm to pass messages between other servers participating in the same newsgroup. When a server receives a message, it relays it to other participating servers that have not yet received it. Data on Usenet is sent using the NNTP protocol.
Duke University students Tom Truscott and Jim Ellis conceived the idea for Usenet in 1979 and it was established in 1980, developed from the general purpose UUCP dial-up network architecture. It is one the oldest computer network communications systems still in use today.
The major set of worldwide newsgroups is contained within nine hierarchies, eight of which are operated under consensual guidelines that govern their administration and naming. The current "Big Eight" are:
- comp.* – computer-related discussions (comp.software, comp.sys.amiga)
- humanities.* – fine arts, literature, and philosophy (humanities.classics, - humanities.design.misc)
- misc.* – miscellaneous topics (misc.education, misc.forsale, misc.kids)
- news.* – discussions and announcements about news (meaning Usenet, not current events) (news.groups, news.admin)
- rec.* – recreation and entertainment (rec.music, rec.arts.movies)
- sci.* – science related discussions (sci.psychology, sci.research)
- soc.* – social discussions (soc.college.org, soc.culture.african)
- talk.* – talk about various controversial topics (talk.religion, talk.politics, talk.origins)
In the 1990s and early 2000s, Internet Service Providers commonly provided Usenet access. Over time, many imposed bandwidth restrictions or download caps, and today most ISPs no longer provide any Usenet quota. Most users obtain access to the Usenet network through a paid subscription.
Usenet users download messages from newsgroups using newsreaders (also called newsclients). Newsreaders download content from newsgroups facilitating an .nzb file, which is a header indexing the content stored in the newsgroup server(s).