An extract on #human_edge
Like all of the original newsreaders and the Usenet software itself, rn was designed for the environment of a large time-shared minicomputer, which users connected to using terminals wired directly to the machine, and where the only networks available were accessed by slow and expensive dial-up modem connections. All of the articles in all of the newsgroups were stored in files on the local disk (known as the "news spool"), and rn could simply read those files directly when presenting them to the user. When local area networks became widespread, it was natural that administrators and users would desire remote access to the news spool, and NNTP, the Network News Transfer Protocol, was developed to serve that need. While working at Baylor College of Medicine, Stan O. Barber developed remote rn (rrn), a set of patches to rn which allowed it to communicate with an NNTP server over a local-area (or even wide-area) network. Barber later took over maintenance responsibility for rn itself from Larry Wall.
As news volumes continued to increase, it became apparent that even KILL files could not possibly keep up with the sheer number of users and articles. A new concept, the threaded newsreader, was needed as users gradually switched from a "read most, kill few" model to "ignore most, read few". By organizing the articles in a newsgroup according to threads of discussion, using headers that had long been present in Usenet articles but practically unused, a threaded newsreader would allow users to keep up with topics and discussions they were interested without having to explicitly deselect uninteresting threads. Kim F. Storm's nn newsreader was the first to implement this new model, and it looked for a while as if nn would do to rn what rn did to readnews. This fate was averted when Wayne Davison developed trn, a set of patches to rn which gave it both threading at the article level and a new user interface that would allow users to select only the threads they desired, while remaining true to the original rn interface philosophy of do the right thing.
An even more recent addition to the rn family has been the addition of scoring, which allows a more complex method of evaluating articles to determine whether the user wishes to read them; originally this was implemented in a code fork of trn called strn, but later this was integrated into the official trn distribution.