A Usenet newsgroup is a repository usually within the Usenet system, for messages posted from many users in different locations. The term may be confusing to some, because it is in fact a discussion group. Newsgroups are technically distinct from, but functionally similar to, discussion forums on the World Wide Web. Newsreader software is used to read newsgroups.
Newsgroups are much like the public message boards on old bulletin board systems. For those readers not familiar with this concept, envision an electronic version of the corkboard in the entrance of your local grocery store.
Despite the advent of file-sharing technologies such as BitTorrent, as well as the increased use of blogs, formal discussion forums, and social networking sites, coupled with a growing number of service providers blocking access to Usenet (see main article), newsgroups continue to be widely used.
Read more about Usenet Newsgroup: Types of Newsgroups, How Newsgroups Work, Hierarchies