Can someone explain Usenet to me? As I understand it, it's not a website. Is it something outside of the WWW? Does it have its own protocol or does it use HTTP? Do you need a dedicated client software for it, similar to IRC? How do/did you register to it? Is it paid? Who hosts it?
An NNTP server had a list of discussion forums: clients connected and got the list, and the user could selectively subscribe to the one's they were interested in. The client would keep track of which messages were read, and so when new ones were posted you'd only see new messages by default.
Each NNTP server could talk to other NNTP servers. They would exchange a list of forums each had, and then the articles had in each forum. Each article/post had a unique ID (basically like the Message-ID in e-mails), and so each could request articles from the other that they did not already have. New messages could be posted to either server and they would 'cross pollinate' (multi-master basically).
Each NNTP server could technically talk to multiple other NNTP servers, so cross-pollination could be very wide, but in the early days with low-kbps modems and expensive long distance, there was a lot of local hierarchical hubs.
There were a few key hubs that had fancy long-distance T1 and such that could transfer across continents and oceans as a bit of a service for the community.