Usenet newsgroups are like conferences or forums on a BBS. Generally, anyone can read and post messages to a newsgroup. There are elaborate newsgroup hierarchies, starting with sci, talk, comp, alt, rec, and so on. Newsgroup postings expire after a certain amount of time regardless of whether you read them or not. Once you read a particular message, you usually don't see it again. Newsgroups have very wide readership but some have a lot of discussion.
Availability of newsgroups varies with particular sites. Ask your site administrator for more information about accessing newsgroups. You may be able to request that additional newsgroups be carried at your site. Popular UNIX newsreaders include rn, nn and tin. If your WWW browser points to a news server, you can use your browser to read these newsgroups.
Note that a Usenet Newsgroup is not the same as a BBS.