The articles that users post to Usenet are organized into topical categories called newsgroups, disscusion groups, or groups. When a user posts an article, it is initially available on that user's news server. Each news server, however, talks to one or more other servers (its "newsfeeds") and exchanges articles with them using NNTP protocol. In this fashion, the article is copied from server to server and (if all goes well) eventually reaches every server in the network.
Newsgroups are typically accessed with special client software that connects to a news server.
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