Most of the groups available in Usenet are free for anyone to post to. In most cases it is up to the poster to observe the rules of posting and not to spam or post off-topic in a newsgroup. However, there are also some groups which have appointed newsgroup administration bodies which ensure everyone is following the rules.
Each administered newsgroup has an assigned email address on which the admin can be reached. The administrators constantly monitor the article flow to the group and if necessary ‘kill,’ or remove, certain articles which they deem inappropriate. The newsgroup administration can also “supersede” any post in the newsgroup by forcefully overwriting it with a newer post. Perhaps even more importantly, newsgroup administrators also oversee the evolution of the major subject hierarchies in Usenet.
Although everyone can create his or her own group in the alt hierarchy, the specialized ones like comp, for example, require the approval of a newsgroup administration body. This ensures there are no bogus groups being created and that the text content of Usenet is preserved as well as possible. The news admins are most often volunteers who dedicate a lot of their personal time to the well being of the Usenet as a whole. These people have been the reason for the sustained phenomenal Usenet growth over the years!