The Interactive Glossary: Defining the Net
Usenet

Usenet refers to the collection of newsgroups (sometimes called the Big Eight hierarchies) and a set of agreed-upon rules for distributing and maintaining them. Thousands of newsgroups exist around the world and the majority of them are a part of Usenet. However, a fairly large number of alternative newsgroups have emerged outside of Usenet.
Learn more: All About Newsgroups