A Usenet newsgroup is a repository usually within the Usenet system, for messages posted from users in different locations using the Internet. They are discussion groups and are not devoted to publishing news. Newsgroups are technically distinct from, but functionally similar to, discussion forums on the World Wide Web. Newsreader software is used to read the content of newsgroups.

Usenet, USENET, or, "in full", User's Network, is a worldwide distributed discussion system available on computers. It was developed from the general-purpose Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Ellis conceived the idea in 1979, and it was established in 1980. Users read and post messages to one or more topic categories, known as newsgroups. Usenet resembles a bulletin board system (BBS) in many respects and is the precursor to the Internet forums that have become widely used. Discussions are threaded, as with web forums and BBSes, though posts are stored on the server sequentially.