A file arrives from everybody at once. Here is how that works
moving 61% of 4.0 GB · 12 seeds · 34 peers · ratio 0.42 · port 6881
A peer to peer transfer takes one file from many machines at once. Nobody holds a master copy and no server hands it out: the file is cut into numbered pieces, every piece carries a fingerprint, and your machine collects them from whoever happens to have them while handing back the ones it already holds.
Piecewise is an independent reference on how that actually works, written for somebody who has a transfer running and has met a word they do not recognize. Every page explains a mechanism and then shows where it appears in your own client window. Nothing is sold here, nothing is downloaded from here, and no page will help anybody find something to copy.
How a BitTorrent transfer works, from magnet link to seeding
Read thisThe swarmWhat the numbers in a client mean
Read thisThe clientsWhat they are and how they differ
Read thisWhy a transfer is slowWhy a transfer is slow, in the order worth checking
Read thisPeer to peerWhat peer to peer means, and what still runs on it
Read thisHow file sharing got hereThe file sharing era, in order
Read thisWhat it carriesWhat the protocol carries every day
Read thisThe four questions people arrive with
failed The transfer still runs, because outgoing calls work. Nobody can call in, so it only reaches peers it dials itself.
waiting Connected to the swarm, and nobody currently online holds a piece you are missing.
complete Uploaded divided by downloaded. One means the swarm got back what it gave; nobody is keeping score about you.
moving The protocol checks every piece against a hash written before the transfer began. The risks are the ordinary ones: where a program came from, and what you then run.
What a transfer looks like from the inside
That is the whole idea. Each block is fetched from whichever machine has it, checked against a fingerprint, and immediately offered back out to the next person who needs it. The more people who want the file, the more machines there are to give it, which is the exact opposite of how one server behaves.
What this site is
A new and independent reference, at a web address a different project used many years ago. It is not that project, is not connected to its authors or to any later owner of this domain, and claims no continuity with any of them. It explains the technology: the protocol, the client software, the numbers in the window, and the documented history of the field. It carries no index or directory of anything, offers no downloads, recommends no service, and gives no legal advice.