1. A newsgroup is a notice board that everyone in the world can see. There are tens of thousands of newsgroups and each group is unique in the world. The client software you use to read a newsgroup is called a news reader (or news client). rtin is a popular text mode reader, while netscape is graphical. pan is an excellent graphical news reader that I use. Newsgroups are named like Internet hosts. One you might be interested in is comp.os.linux.announce. The comp is the broadest subject description for computers; os stands for operating systems; and so on. Many other linux newsgroups are devoted to various LINUX issues. Newsgroups servers are big hungry beasts. They form a tree-like structure on the Internet. When you send mail to a newsgroup it takes about a day or so for the mail you sent to propagate to every other server in the world. Likewise, you can see a list of all the messages posted to each newsgroup by anyone anywhere. What's the difference between a newsgroup and a mailing list? The advantage of a newsgroup is that you don't have to download the messages you are not interested in. If you are on a mailing list, you get all the mail sent to the list. With a newsgroup you can look at the message list and retrieve only the messages you are interested in. Why not just put the mailing list on a web page? If you did, then everyone in the world would have to go over international links to get to the web page. It would load the server in proportion to the number of subscribers. This is exactly what SlashDot is. However, your newsgroup server is local, so you retrieve mail over a faster link and save Internet traffic. From Rute-Users-Guide

2. These are the bulletin boards of the Internet. There are around 20,000 groups covering every subject under the sun. Most IAPs have a newsgroup server which periodically takes all new messages from a newsgroup feed and adds the messages which have been posted by its own users. To access the newsgroups stored on your IAPs newsgroup server you need a newsreader program. From Glossary of Distance Education and Internet Terminology