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?
The basic concept is simply copying and forwarding email-like messages, grouped into a hierarchical set of newsgroup feeds. A host would subscribe to other hosts, and would allow other hosts to subscribe to their own feeds. And then just push/pull this through the network.
Originally, this was done all with shell scripts dialing up remote hosts by modem and copying compressed datasets nightly. This developed into a full suite of protocols called UUCP. Later, Internet protocols like the Network News Transfer Protocol started carrying some, then all, of the traffic.
In principle, it is unregistered, unpaid, and decentralized. You start exchanging with someone else who has the newsgroups you want to send and receive.
In practice, both in the past and now, you subscribe, usually commercially, to one of the services with the bandwidth and storage to host a reasonable portion of Usenet. ISPs often provided NNTP Usenet service into the early 2000s, along with SMTP/POP for email.