/jp/ - Otaku Culture

>>23153792
>>23153687
Couldn't find a concise explanation, so I wrote this up.
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A torrent file exists independently of seeders (active peers who are uploading the torrent's data to others). What a torrent file provides is:
1. Filenames and descriptions
2. The structure of "pieces" - the individual units of the data that you send/receive/confirm with other peers.
3. Announce URL - the URL of the tracker. The tracker's job is to coordinate the transfer of data between peers.
4. Optionally, backup announce URLs (most popular torrents will use a handful of trackers), creation date, a comment, and the name and version of the program used to make the torrent.

Also, you don't need either an announce server or even a torrent file if the torrent is not marked as private (for private trackers), and at least one seeder has DHT enabled. This is how "trackerless" torrents and magnet links are able to function.
DHT (distributed hash table) allows peers to send at least a partial listing of available peers to a "bootstrap node" which agglomerates this information and provides it upon request. So if the associated trackers are down, a client can enable DHT and use the routing information provided from the bootstrap node(s) to contact a peer. PEX (Peer exchange) can also be used to directly transfer this information between peers after initial peer discovery, but isn't required. The main caveat to not using a tracker is less efficient/slower uploading/downloading, as the coordination of peers is decentralized.

>how tf does downloading a torrent when theres no seeds work?
Your client will wait indefinitely until the associated tracker(s) provides you with a peer from which to leech (download). If none exist, you're SOL.