In: software, technology.
Also: e-mail, Torrents.

Usenet 🧍‍♂️

Usenet (User's Network), is a worldwide distributed discussion system available on computers. It was developed from the general-purpose Unix-to-Unix Copy (UUCP) dial-up network architecture. Tom Truscott and Jim Ellis conceived the idea in 1979, and it was established in 1980.
USENET grew to include thousands of discussion groups (called newsgroups), stored on special Internet servers, and millions of users. Users read and write posts, called articles, using software called a newsreader. (At the height of USENET's popularity, Web browsers and e-mail software typically contained a built-in newsreader, eliminating the need for a separate program).
Usenet is the predecesor of modern forums and Reddit communities.

Community

https://reddit.com/r/usenet/
https://usenet.community/ -- to Discord

Clients

NZBGet

https://nzbget.com
https://github.com/nzbgetcom/nzbget

SABnzbd

https://sabnzbd.org
https://github.com/sabnzbd/sabnzbd

Indexers

There's tons more, just a few popular ones: