A newsgroup is an electronic discussion group consisting of collections of related postings (also called articles) on a particular topic that are posted to a news server which then distributes them to other participating servers. There are thousands of newsgroups covering a wide range of subjects. You must subscribe to a newsgroup in order to participate in it or to track the discussion on an on-going basis. Unlike a magazine or newspaper subscription, a subscription to a newsgroup is free.
It is simply a global bulletin board where like-minded people share ideas, information and experiences by email.