Usenet in a Nutshell

Usenet is a distributed discussion system. Using a special program called a newsreader, a user accesses a news server to read and post email-like messages called articles. These articles are then exchanged back and forth with other news servers throughout the world. In this way, articles propagate from one news server to another throughout the entire Usenet system.

Articles are organized into categories called groups. In discussion groups, most articles are responses to another article. The set of articles which can be traced to one single non-reply article is called a thread. When articles are organized into threads, it is much easier to follow a single discussion.

Articles are routed around Usenet based on the information contained in the article header, which is the first part of an article that contains information like the subject, author, date and routing information. To save time and bandwidth, most newsreaders first download just the article headers to sort and thread them. The user selects an article of interest from the list of headers and then downloads the article body to read.

Usenet was originally created to distribute text content encoded in 7-bit ASCII. With additional encoding programs, multiple posts per chunk and other various tricks, it became possible to send binary data through Usenet. Groups that allow for binary content or binaries are called binary groups.