Trackers are , not file storages. They don’t know what’s in the files — only that certain IP addresses want certain hash values. They are the town criers of the torrent world: “Peer A seeks data block 42! Peer B has it!”
Your client sends an "announce" request to the tracker, sharing your IP and what progress you've made on the download. what are trackers on torrents
Telling your torrent client which other users have the specific "pieces" of the file you are missing. Trackers are , not file storages