A newsgroup, or Usenet newsgroup, is a depository within the Usenet system for messages posted by multiple users in disparate locations. The term has caused some confusion at times, because a newsgroup is really just a discussion group, and not a news reporting function as the name might imply. There are two varsities of newsgroup, text and binary, although there’s no real difference between the two from a technical perspective.
Newsgroups generally are focused on a specific topic, but different newsgroups have varying levels of tolerance for posting of off-topic messages; some allow users to post essentially anything that they themselves deem relevant, while others are more narrowly focused and discourage off-topic postings. The administrator of a newsgroup’s news server (the news admin) controls how long articles and discussions are archived on the news server before being deleted.
Although newsgroups were not originally created to distribute binary files, that has become one of their core functions and uses over time. Since every user in a newsgroup is drawing on the bandwidth of his own news server, providing control over the user’s download speed, unlike in a peer-to-peer (P2P) system, wherein the speed of download varies greatly depending on the resources of the user sharing the file. Also unlike p2p, where sharing is generally expected of all users, in a newsgroup context it is considered completely acceptable to only download files without sharing any (something that’s referred to as leeching in a p2p context).