newsreaders are programs used to access and read the news. They usually fetch the news from the newsserver.
All newsreaders are capable to perform at least the following tasks:
newsreaders use the configuration file
.newsrcto find out which newsgroups you subscribe to. It is created the first time the newsreader is invoked.
That file may be viewed/edited with any text editor to find out which newsgroup is available to be read on that system.