Usenet newsgroups are internet discussion groups. At first usenet newsgroups were to share or publish text information/foundings on just about any topic you can imagine. Nowadays usenet newsgroups are used to post binary (movies, music and games) files on and still it is used to publish text information and foundings. Usenet consists of 9 hierarchies, if you don't know what hierarchies are, find out under usenet explained.
Usenet Newsgroup Access
Underneath these hierarchies usenet newsgroups were ordened. Such as alt.binaries.boneless and alt.binaries.tv. In these usenet newsgroups, posts (such as movies, games and music) are uploaded and shared on all servers (usenet servers), which are giving access to these usenet newsgroups. If you are connected with a usenet server which is giving access to usenet newsgroups, you are able to download all the latest posts (such as movies, games, music) in these usenet newsgroups. You can download them because you have access to these usenet newsgroups via your server (usenet server).