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).
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).