A tracker (a server/website used to track torrents uploaded to it by members; torrent clients require these tracker servers to know how to download the torrent) that is private (not freely accesible to the general public, typically needing a registered account).

Not sure if it was just changed, but I see it has a Mature 17+ rating.

Just curious, for everyone saying they switched to jellyfin, were you using the free version of plex?