What is Usenet?
Usenet is the largest public discussion forum in the world. Messages are transferred between servers distributed all over the Net, using NNTP (Network News Transfer Protocol).
Usenet Info Center
UCS Knowledge Base

What are Newsgroups? Usenet is organized into a hierarchical system of Newsgroups, each devoted to a topic, with a naming system similar to the domain-name system. There are tens of thousands of newsgroups, although not all are carried on every server. The sites below can help you choose a newsgroup, but keep in mind you'll need to have a news server specified in your reader to access the actual messages.
Anchorman Hierarchical News Reader
CyberFiber(r) Newsgroups
Usenet Info Center Launch Pad

Software You'll Need
Popular browsers have newsgroup readers built-in, but you may want the extra functionality of a dedicated news reader. You may also need to configure the reader to point to your news server.
Reviews of News Reader Software

Before Posting Messages . . .
Many newsgroups are moderated, meaning someone reads each message before it gets to the group at large, and deletes those deemed off-topic or abusive. Some groups are self-moderated, meaning if you post an off-topic message you'll get flamed by other members. Completely unmoderated groups can be overrun with spam, to the point of being useless. Be sure to read a newsgroup's FAQ before posting, if you want to avoid annoying the group.

Frequently Asked Questions...and Answers
These are searchable collections of FAQs from various Usenet newsgroups. Newsgroup FAQs usually tell you what the group is about and what the rules are for posting messages, in addition to answering common questions devoted to the newsgroup topic itself.
Usenet Info Center FAQ
FAQFinder Project
USENET Newsgroup FAQs

Publicly Accessible News Servers
If your ISP does not carry a specific newsgroup you need, or if you don't have access to a news server at all, check out these lists of "open" NNTP servers.
AMP Productions List of Open NNTP Usenet Sites
Newzbot
Dark Demon's Open NNTP Sites
Schedule96%
Tony's Public News Server Page

Web-Based Usenet Services
These services let you use the Web to browse, search, and post messages in the Usenet newsgroups. No news reader is necessary.
Alta Vista News Groups Search Engine
DejaNews
Excite News Group Search Engine
Reference.com
Zippo's News Service

Starting Points
Here are some good starting points. . .click on one of the links below to see if your browser is configured with a news server.
news.announce.newusers
news.newusers.questions