Usenet newsgroup

A Usenet newsgroup is a usually within the Usenet system, for messages posted from many users in different locations using Internet. Despite the name, newsgroups are discussion groups, and are not devoted to publishing news, but were when the internet was young. Newsgroups are technically distinct from, but functionally similar to, discussion forums on the World Wide Web. Newsreader software is used to read newsgroups.

Before the uptake of the World Wide Web, Usenet newsgroups were among the most popular Internet services, and have retained their noncommercial nature in contrast to the increasingly ad-laden web. In recent years, this form of open discussion on the Internet has lost considerable ground to individually-operated browser-accessible forums and big media social networks such as Facebook and Twitter.

Transmission within and at the bounds of the network uses the (NNTP), an Internet standard.

Newsgroups generally come in either of two types, binary or text. There is no technical difference between the two, but the naming differentiation allows users and servers with limited facilities to minimize network bandwidth usage. Generally, Usenet conventions and rules are enacted with the primary intention of minimizing the overall amount of network traffic and resource usage. Typically, the newsgroup is focused on a particular topic of interest. A message sent for publication on a newsgroup is called a "post". Some newsgroups allow posts on a wide variety of themes, regarding anything a member chooses to discuss as on-topic, while others keep more strictly to their particular subject, frowning on off-topic posts. The news admin (the administrator of a news server) decides how long posts are kept on his server before being expired (deleted). Different servers will have different retention times for the same newsgroup; some may keep posts for as little as one or two weeks, others may hold them for many months. Some admins keep posts in local or technical newsgroups around longer than posts in other newsgroups.

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Wikipedia